kernel/drivers/md/raid5.c

   1 /*
   2  * raid5.c : Multiple Devices driver for Linux
   3  *         Copyright (C) 1996, 1997 Ingo Molnar, Miguel de Icaza, Gadi Oxman
   4  *         Copyright (C) 1999, 2000 Ingo Molnar
   5  *         Copyright (C) 2002, 2003 H. Peter Anvin
   6  *
   7  * RAID-4/5/6 management functions.
   8  * Thanks to Penguin Computing for making the RAID-6 development possible
   9  * by donating a test server!
  10  *
  11  * This program is free software; you can redistribute it and/or modify
  12  * it under the terms of the GNU General Public License as published by
  13  * the Free Software Foundation; either version 2, or (at your option)
  14  * any later version.
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * (for example /usr/src/linux/COPYING); if not, write to the Free
  18  * Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  19  */
  20
  21 /*
  22  * BITMAP UNPLUGGING:
  23  *
  24  * The sequencing for updating the bitmap reliably is a little
  25  * subtle (and I got it wrong the first time) so it deserves some
  26  * explanation.
  27  *
  28  * We group bitmap updates into batches.  Each batch has a number.
  29  * We may write out several batches at once, but that isn't very important.
  30  * conf->seq_write is the number of the last batch successfully written.
  31  * conf->seq_flush is the number of the last batch that was closed to
  32  *    new additions.
  33  * When we discover that we will need to write to any block in a stripe
  34  * (in add_stripe_bio) we update the in-memory bitmap and record in sh->bm_seq
  35  * the number of the batch it will be in. This is seq_flush+1.
  36  * When we are ready to do a write, if that batch hasn't been written yet,
  37  *   we plug the array and queue the stripe for later.
  38  * When an unplug happens, we increment bm_flush, thus closing the current
  39  *   batch.
  40  * When we notice that bm_flush > bm_write, we write out all pending updates
  41  * to the bitmap, and advance bm_write to where bm_flush was.
  42  * This may occasionally write a bit out twice, but is sure never to
  43  * miss any bits.
  44  */
  45
  46 #include <linux/blkdev.h>
  47 #include <linux/kthread.h>
  48 #include <linux/raid/pq.h>
  49 #include <linux/async_tx.h>
  50 #include <linux/module.h>
  51 #include <linux/async.h>
  52 #include <linux/seq_file.h>
  53 #include <linux/cpu.h>
  54 #include <linux/slab.h>
  55 #include <linux/ratelimit.h>
  56 #include <linux/nodemask.h>
  57 #include <linux/flex_array.h>
  58 #include <trace/events/block.h>
  59
  60 #include "md.h"
  61 #include "raid5.h"
  62 #include "raid0.h"
  63 #include "bitmap.h"
  64
  65 #define cpu_to_group(cpu) cpu_to_node(cpu)
  66 #define ANY_GROUP NUMA_NO_NODE
  67
  68 static bool devices_handle_discard_safely = false;
  69 module_param(devices_handle_discard_safely, bool, 0644);
  70 MODULE_PARM_DESC(devices_handle_discard_safely,
  71                  "Set to Y if all devices in each array reliably return zeroes on reads from discarded regions");
  72 static struct workqueue_struct *raid5_wq;
  73 /*
  74  * Stripe cache
  75  */
  76
  77 #define NR_STRIPES              256
  78 #define STRIPE_SIZE             PAGE_SIZE
  79 #define STRIPE_SHIFT            (PAGE_SHIFT - 9)
  80 #define STRIPE_SECTORS          (STRIPE_SIZE>>9)
  81 #define IO_THRESHOLD            1
  82 #define BYPASS_THRESHOLD        1
  83 #define NR_HASH                 (PAGE_SIZE / sizeof(struct hlist_head))
  84 #define HASH_MASK               (NR_HASH - 1)
  85 #define MAX_STRIPE_BATCH        8
  86
  87 static inline struct hlist_head *stripe_hash(struct r5conf *conf, sector_t sect)
  88 {
  89         int hash = (sect >> STRIPE_SHIFT) & HASH_MASK;
  90         return &conf->stripe_hashtbl[hash];
  91 }
  92
  93 static inline int stripe_hash_locks_hash(sector_t sect)
  94 {
  95         return (sect >> STRIPE_SHIFT) & STRIPE_HASH_LOCKS_MASK;
  96 }
  97
  98 static inline void lock_device_hash_lock(struct r5conf *conf, int hash)
  99 {
 100         spin_lock_irq(conf->hash_locks + hash);
 101         spin_lock(&conf->device_lock);
 102 }
 103
 104 static inline void unlock_device_hash_lock(struct r5conf *conf, int hash)
 105 {
 106         spin_unlock(&conf->device_lock);
 107         spin_unlock_irq(conf->hash_locks + hash);
 108 }
 109
 110 static inline void lock_all_device_hash_locks_irq(struct r5conf *conf)
 111 {
 112         int i;
 113         local_irq_disable();
 114         spin_lock(conf->hash_locks);
 115         for (i = 1; i < NR_STRIPE_HASH_LOCKS; i++)
 116                 spin_lock_nest_lock(conf->hash_locks + i, conf->hash_locks);
 117         spin_lock(&conf->device_lock);
 118 }
 119
 120 static inline void unlock_all_device_hash_locks_irq(struct r5conf *conf)
 121 {
 122         int i;
 123         spin_unlock(&conf->device_lock);
 124         for (i = NR_STRIPE_HASH_LOCKS; i; i--)
 125                 spin_unlock(conf->hash_locks + i - 1);
 126         local_irq_enable();
 127 }
 128
 129 /* bio's attached to a stripe+device for I/O are linked together in bi_sector
 130  * order without overlap.  There may be several bio's per stripe+device, and
 131  * a bio could span several devices.
 132  * When walking this list for a particular stripe+device, we must never proceed
 133  * beyond a bio that extends past this device, as the next bio might no longer
 134  * be valid.
 135  * This function is used to determine the 'next' bio in the list, given the sector
 136  * of the current stripe+device
 137  */
 138 static inline struct bio *r5_next_bio(struct bio *bio, sector_t sector)
 139 {
 140         int sectors = bio_sectors(bio);
 141         if (bio->bi_iter.bi_sector + sectors < sector + STRIPE_SECTORS)
 142                 return bio->bi_next;
 143         else
 144                 return NULL;
 145 }
 146
 147 /*
 148  * We maintain a biased count of active stripes in the bottom 16 bits of
 149  * bi_phys_segments, and a count of processed stripes in the upper 16 bits
 150  */
 151 static inline int raid5_bi_processed_stripes(struct bio *bio)
 152 {
 153         atomic_t *segments = (atomic_t *)&bio->bi_phys_segments;
 154         return (atomic_read(segments) >> 16) & 0xffff;
 155 }
 156
 157 static inline int raid5_dec_bi_active_stripes(struct bio *bio)
 158 {
 159         atomic_t *segments = (atomic_t *)&bio->bi_phys_segments;
 160         return atomic_sub_return(1, segments) & 0xffff;
 161 }
 162
 163 static inline void raid5_inc_bi_active_stripes(struct bio *bio)
 164 {
 165         atomic_t *segments = (atomic_t *)&bio->bi_phys_segments;
 166         atomic_inc(segments);
 167 }
 168
 169 static inline void raid5_set_bi_processed_stripes(struct bio *bio,
 170         unsigned int cnt)
 171 {
 172         atomic_t *segments = (atomic_t *)&bio->bi_phys_segments;
 173         int old, new;
 174
 175         do {
 176                 old = atomic_read(segments);
 177                 new = (old & 0xffff) | (cnt << 16);
 178         } while (atomic_cmpxchg(segments, old, new) != old);
 179 }
 180
 181 static inline void raid5_set_bi_stripes(struct bio *bio, unsigned int cnt)
 182 {
 183         atomic_t *segments = (atomic_t *)&bio->bi_phys_segments;
 184         atomic_set(segments, cnt);
 185 }
 186
 187 /* Find first data disk in a raid6 stripe */
 188 static inline int raid6_d0(struct stripe_head *sh)
 189 {
 190         if (sh->ddf_layout)
 191                 /* ddf always start from first device */
 192                 return 0;
 193         /* md starts just after Q block */
 194         if (sh->qd_idx == sh->disks - 1)
 195                 return 0;
 196         else
 197                 return sh->qd_idx + 1;
 198 }
 199 static inline int raid6_next_disk(int disk, int raid_disks)
 200 {
 201         disk++;
 202         return (disk < raid_disks) ? disk : 0;
 203 }
 204
 205 /* When walking through the disks in a raid5, starting at raid6_d0,
 206  * We need to map each disk to a 'slot', where the data disks are slot
 207  * 0 .. raid_disks-3, the parity disk is raid_disks-2 and the Q disk
 208  * is raid_disks-1.  This help does that mapping.
 209  */
 210 static int raid6_idx_to_slot(int idx, struct stripe_head *sh,
 211                              int *count, int syndrome_disks)
 212 {
 213         int slot = *count;
 214
 215         if (sh->ddf_layout)
 216                 (*count)++;
 217         if (idx == sh->pd_idx)
 218                 return syndrome_disks;
 219         if (idx == sh->qd_idx)
 220                 return syndrome_disks + 1;
 221         if (!sh->ddf_layout)
 222                 (*count)++;
 223         return slot;
 224 }
 225
 226 static void return_io(struct bio *return_bi)
 227 {
 228         struct bio *bi = return_bi;
 229         while (bi) {
 230
 231                 return_bi = bi->bi_next;
 232                 bi->bi_next = NULL;
 233                 bi->bi_iter.bi_size = 0;
 234                 trace_block_bio_complete(bdev_get_queue(bi->bi_bdev),
 235                                          bi, 0);
 236                 bio_endio(bi, 0);
 237                 bi = return_bi;
 238         }
 239 }
 240
 241 static void print_raid5_conf (struct r5conf *conf);
 242
 243 static int stripe_operations_active(struct stripe_head *sh)
 244 {
 245         return sh->check_state || sh->reconstruct_state ||
 246                test_bit(STRIPE_BIOFILL_RUN, &sh->state) ||
 247                test_bit(STRIPE_COMPUTE_RUN, &sh->state);
 248 }
 249
 250 static void raid5_wakeup_stripe_thread(struct stripe_head *sh)
 251 {
 252         struct r5conf *conf = sh->raid_conf;
 253         struct r5worker_group *group;
 254         int thread_cnt;
 255         int i, cpu = sh->cpu;
 256
 257         if (!cpu_online(cpu)) {
 258                 cpu = cpumask_any(cpu_online_mask);
 259                 sh->cpu = cpu;
 260         }
 261
 262         if (list_empty(&sh->lru)) {
 263                 struct r5worker_group *group;
 264                 group = conf->worker_groups + cpu_to_group(cpu);
 265                 list_add_tail(&sh->lru, &group->handle_list);
 266                 group->stripes_cnt++;
 267                 sh->group = group;
 268         }
 269
 270         if (conf->worker_cnt_per_group == 0) {
 271                 md_wakeup_thread(conf->mddev->thread);
 272                 return;
 273         }
 274
 275         group = conf->worker_groups + cpu_to_group(sh->cpu);
 276
 277         group->workers[0].working = true;
 278         /* at least one worker should run to avoid race */
 279         queue_work_on(sh->cpu, raid5_wq, &group->workers[0].work);
 280
 281         thread_cnt = group->stripes_cnt / MAX_STRIPE_BATCH - 1;
 282         /* wakeup more workers */
 283         for (i = 1; i < conf->worker_cnt_per_group && thread_cnt > 0; i++) {
 284                 if (group->workers[i].working == false) {
 285                         group->workers[i].working = true;
 286                         queue_work_on(sh->cpu, raid5_wq,
 287                                       &group->workers[i].work);
 288                         thread_cnt--;
 289                 }
 290         }
 291 }
 292
 293 static void do_release_stripe(struct r5conf *conf, struct stripe_head *sh,
 294                               struct list_head *temp_inactive_list)
 295 {
 296         BUG_ON(!list_empty(&sh->lru));
 297         BUG_ON(atomic_read(&conf->active_stripes)==0);
 298         if (test_bit(STRIPE_HANDLE, &sh->state)) {
 299                 if (test_bit(STRIPE_DELAYED, &sh->state) &&
 300                     !test_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
 301                         list_add_tail(&sh->lru, &conf->delayed_list);
 302                 else if (test_bit(STRIPE_BIT_DELAY, &sh->state) &&
 303                            sh->bm_seq - conf->seq_write > 0)
 304                         list_add_tail(&sh->lru, &conf->bitmap_list);
 305                 else {
 306                         clear_bit(STRIPE_DELAYED, &sh->state);
 307                         clear_bit(STRIPE_BIT_DELAY, &sh->state);
 308                         if (conf->worker_cnt_per_group == 0) {
 309                                 list_add_tail(&sh->lru, &conf->handle_list);
 310                         } else {
 311                                 raid5_wakeup_stripe_thread(sh);
 312                                 return;
 313                         }
 314                 }
 315                 md_wakeup_thread(conf->mddev->thread);
 316         } else {
 317                 BUG_ON(stripe_operations_active(sh));
 318                 if (test_and_clear_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
 319                         if (atomic_dec_return(&conf->preread_active_stripes)
 320                             < IO_THRESHOLD)
 321                                 md_wakeup_thread(conf->mddev->thread);
 322                 atomic_dec(&conf->active_stripes);
 323                 if (!test_bit(STRIPE_EXPANDING, &sh->state))
 324                         list_add_tail(&sh->lru, temp_inactive_list);
 325         }
 326 }
 327
 328 static void __release_stripe(struct r5conf *conf, struct stripe_head *sh,
 329                              struct list_head *temp_inactive_list)
 330 {
 331         if (atomic_dec_and_test(&sh->count))
 332                 do_release_stripe(conf, sh, temp_inactive_list);
 333 }
 334
 335 /*
 336  * @hash could be NR_STRIPE_HASH_LOCKS, then we have a list of inactive_list
 337  *
 338  * Be careful: Only one task can add/delete stripes from temp_inactive_list at
 339  * given time. Adding stripes only takes device lock, while deleting stripes
 340  * only takes hash lock.
 341  */
 342 static void release_inactive_stripe_list(struct r5conf *conf,
 343                                          struct list_head *temp_inactive_list,
 344                                          int hash)
 345 {
 346         int size;
 347         bool do_wakeup = false;
 348         unsigned long flags;
 349
 350         if (hash == NR_STRIPE_HASH_LOCKS) {
 351                 size = NR_STRIPE_HASH_LOCKS;
 352                 hash = NR_STRIPE_HASH_LOCKS - 1;
 353         } else
 354                 size = 1;
 355         while (size) {
 356                 struct list_head *list = &temp_inactive_list[size - 1];
 357
 358                 /*
 359                  * We don't hold any lock here yet, get_active_stripe() might
 360                  * remove stripes from the list
 361                  */
 362                 if (!list_empty_careful(list)) {
 363                         spin_lock_irqsave(conf->hash_locks + hash, flags);
 364                         if (list_empty(conf->inactive_list + hash) &&
 365                             !list_empty(list))
 366                                 atomic_dec(&conf->empty_inactive_list_nr);
 367                         list_splice_tail_init(list, conf->inactive_list + hash);
 368                         do_wakeup = true;
 369                         spin_unlock_irqrestore(conf->hash_locks + hash, flags);
 370                 }
 371                 size--;
 372                 hash--;
 373         }
 374
 375         if (do_wakeup) {
 376                 wake_up(&conf->wait_for_stripe);
 377                 if (conf->retry_read_aligned)
 378                         md_wakeup_thread(conf->mddev->thread);
 379         }
 380 }
 381
 382 /* should hold conf->device_lock already */
 383 static int release_stripe_list(struct r5conf *conf,
 384                                struct list_head *temp_inactive_list)
 385 {
 386         struct stripe_head *sh;
 387         int count = 0;
 388         struct llist_node *head;
 389
 390         head = llist_del_all(&conf->released_stripes);
 391         head = llist_reverse_order(head);
 392         while (head) {
 393                 int hash;
 394
 395                 sh = llist_entry(head, struct stripe_head, release_list);
 396                 head = llist_next(head);
 397                 /* sh could be readded after STRIPE_ON_RELEASE_LIST is cleard */
 398                 smp_mb();
 399                 clear_bit(STRIPE_ON_RELEASE_LIST, &sh->state);
 400                 /*
 401                  * Don't worry the bit is set here, because if the bit is set
 402                  * again, the count is always > 1. This is true for
 403                  * STRIPE_ON_UNPLUG_LIST bit too.
 404                  */
 405                 hash = sh->hash_lock_index;
 406                 __release_stripe(conf, sh, &temp_inactive_list[hash]);
 407                 count++;
 408         }
 409
 410         return count;
 411 }
 412
 413 static void release_stripe(struct stripe_head *sh)
 414 {
 415         struct r5conf *conf = sh->raid_conf;
 416         unsigned long flags;
 417         struct list_head list;
 418         int hash;
 419         bool wakeup;
 420
 421         /* Avoid release_list until the last reference.
 422          */
 423         if (atomic_add_unless(&sh->count, -1, 1))
 424                 return;
 425
 426         if (unlikely(!conf->mddev->thread) ||
 427                 test_and_set_bit(STRIPE_ON_RELEASE_LIST, &sh->state))
 428                 goto slow_path;
 429         wakeup = llist_add(&sh->release_list, &conf->released_stripes);
 430         if (wakeup)
 431                 md_wakeup_thread(conf->mddev->thread);
 432         return;
 433 slow_path:
 434         local_irq_save(flags);
 435         /* we are ok here if STRIPE_ON_RELEASE_LIST is set or not */
 436         if (atomic_dec_and_lock(&sh->count, &conf->device_lock)) {
 437                 INIT_LIST_HEAD(&list);
 438                 hash = sh->hash_lock_index;
 439                 do_release_stripe(conf, sh, &list);
 440                 spin_unlock(&conf->device_lock);
 441                 release_inactive_stripe_list(conf, &list, hash);
 442         }
 443         local_irq_restore(flags);
 444 }
 445
 446 static inline void remove_hash(struct stripe_head *sh)
 447 {
 448         pr_debug("remove_hash(), stripe %llu\n",
 449                 (unsigned long long)sh->sector);
 450
 451         hlist_del_init(&sh->hash);
 452 }
 453
 454 static inline void insert_hash(struct r5conf *conf, struct stripe_head *sh)
 455 {
 456         struct hlist_head *hp = stripe_hash(conf, sh->sector);
 457
 458         pr_debug("insert_hash(), stripe %llu\n",
 459                 (unsigned long long)sh->sector);
 460
 461         hlist_add_head(&sh->hash, hp);
 462 }
 463
 464 /* find an idle stripe, make sure it is unhashed, and return it. */
 465 static struct stripe_head *get_free_stripe(struct r5conf *conf, int hash)
 466 {
 467         struct stripe_head *sh = NULL;
 468         struct list_head *first;
 469
 470         if (list_empty(conf->inactive_list + hash))
 471                 goto out;
 472         first = (conf->inactive_list + hash)->next;
 473         sh = list_entry(first, struct stripe_head, lru);
 474         list_del_init(first);
 475         remove_hash(sh);
 476         atomic_inc(&conf->active_stripes);
 477         BUG_ON(hash != sh->hash_lock_index);
 478         if (list_empty(conf->inactive_list + hash))
 479                 atomic_inc(&conf->empty_inactive_list_nr);
 480 out:
 481         return sh;
 482 }
 483
 484 static void shrink_buffers(struct stripe_head *sh)
 485 {
 486         struct page *p;
 487         int i;
 488         int num = sh->raid_conf->pool_size;
 489
 490         for (i = 0; i < num ; i++) {
 491                 WARN_ON(sh->dev[i].page != sh->dev[i].orig_page);
 492                 p = sh->dev[i].page;
 493                 if (!p)
 494                         continue;
 495                 sh->dev[i].page = NULL;
 496                 put_page(p);
 497         }
 498 }
 499
 500 static int grow_buffers(struct stripe_head *sh, gfp_t gfp)
 501 {
 502         int i;
 503         int num = sh->raid_conf->pool_size;
 504
 505         for (i = 0; i < num; i++) {
 506                 struct page *page;
 507
 508                 if (!(page = alloc_page(gfp))) {
 509                         return 1;
 510                 }
 511                 sh->dev[i].page = page;
 512                 sh->dev[i].orig_page = page;
 513         }
 514         return 0;
 515 }
 516
 517 static void raid5_build_block(struct stripe_head *sh, int i, int previous);
 518 static void stripe_set_idx(sector_t stripe, struct r5conf *conf, int previous,
 519                             struct stripe_head *sh);
 520
 521 static void init_stripe(struct stripe_head *sh, sector_t sector, int previous)
 522 {
 523         struct r5conf *conf = sh->raid_conf;
 524         int i, seq;
 525
 526         BUG_ON(atomic_read(&sh->count) != 0);
 527         BUG_ON(test_bit(STRIPE_HANDLE, &sh->state));
 528         BUG_ON(stripe_operations_active(sh));
 529         BUG_ON(sh->batch_head);
 530
 531         pr_debug("init_stripe called, stripe %llu\n",
 532                 (unsigned long long)sector);
 533 retry:
 534         seq = read_seqcount_begin(&conf->gen_lock);
 535         sh->generation = conf->generation - previous;
 536         sh->disks = previous ? conf->previous_raid_disks : conf->raid_disks;
 537         sh->sector = sector;
 538         stripe_set_idx(sector, conf, previous, sh);
 539         sh->state = 0;
 540
 541         for (i = sh->disks; i--; ) {
 542                 struct r5dev *dev = &sh->dev[i];
 543
 544                 if (dev->toread || dev->read || dev->towrite || dev->written ||
 545                     test_bit(R5_LOCKED, &dev->flags)) {
 546                         printk(KERN_ERR "sector=%llx i=%d %p %p %p %p %d\n",
 547                                (unsigned long long)sh->sector, i, dev->toread,
 548                                dev->read, dev->towrite, dev->written,
 549                                test_bit(R5_LOCKED, &dev->flags));
 550                         WARN_ON(1);
 551                 }
 552                 dev->flags = 0;
 553                 raid5_build_block(sh, i, previous);
 554         }
 555         if (read_seqcount_retry(&conf->gen_lock, seq))
 556                 goto retry;
 557         sh->overwrite_disks = 0;
 558         insert_hash(conf, sh);
 559         sh->cpu = smp_processor_id();
 560         set_bit(STRIPE_BATCH_READY, &sh->state);
 561 }
 562
 563 static struct stripe_head *__find_stripe(struct r5conf *conf, sector_t sector,
 564                                          short generation)
 565 {
 566         struct stripe_head *sh;
 567
 568         pr_debug("__find_stripe, sector %llu\n", (unsigned long long)sector);
 569         hlist_for_each_entry(sh, stripe_hash(conf, sector), hash)
 570                 if (sh->sector == sector && sh->generation == generation)
 571                         return sh;
 572         pr_debug("__stripe %llu not in cache\n", (unsigned long long)sector);
 573         return NULL;
 574 }
 575
 576 /*
 577  * Need to check if array has failed when deciding whether to:
 578  *  - start an array
 579  *  - remove non-faulty devices
 580  *  - add a spare
 581  *  - allow a reshape
 582  * This determination is simple when no reshape is happening.
 583  * However if there is a reshape, we need to carefully check
 584  * both the before and after sections.
 585  * This is because some failed devices may only affect one
 586  * of the two sections, and some non-in_sync devices may
 587  * be insync in the section most affected by failed devices.
 588  */
 589 static int calc_degraded(struct r5conf *conf)
 590 {
 591         int degraded, degraded2;
 592         int i;
 593
 594         rcu_read_lock();
 595         degraded = 0;
 596         for (i = 0; i < conf->previous_raid_disks; i++) {
 597                 struct md_rdev *rdev = rcu_dereference(conf->disks[i].rdev);
 598                 if (rdev && test_bit(Faulty, &rdev->flags))
 599                         rdev = rcu_dereference(conf->disks[i].replacement);
 600                 if (!rdev || test_bit(Faulty, &rdev->flags))
 601                         degraded++;
 602                 else if (test_bit(In_sync, &rdev->flags))
 603                         ;
 604                 else
 605                         /* not in-sync or faulty.
 606                          * If the reshape increases the number of devices,
 607                          * this is being recovered by the reshape, so
 608                          * this 'previous' section is not in_sync.
 609                          * If the number of devices is being reduced however,
 610                          * the device can only be part of the array if
 611                          * we are reverting a reshape, so this section will
 612                          * be in-sync.
 613                          */
 614                         if (conf->raid_disks >= conf->previous_raid_disks)
 615                                 degraded++;
 616         }
 617         rcu_read_unlock();
 618         if (conf->raid_disks == conf->previous_raid_disks)
 619                 return degraded;
 620         rcu_read_lock();
 621         degraded2 = 0;
 622         for (i = 0; i < conf->raid_disks; i++) {
 623                 struct md_rdev *rdev = rcu_dereference(conf->disks[i].rdev);
 624                 if (rdev && test_bit(Faulty, &rdev->flags))
 625                         rdev = rcu_dereference(conf->disks[i].replacement);
 626                 if (!rdev || test_bit(Faulty, &rdev->flags))
 627                         degraded2++;
 628                 else if (test_bit(In_sync, &rdev->flags))
 629                         ;
 630                 else
 631                         /* not in-sync or faulty.
 632                          * If reshape increases the number of devices, this
 633                          * section has already been recovered, else it
 634                          * almost certainly hasn't.
 635                          */
 636                         if (conf->raid_disks <= conf->previous_raid_disks)
 637                                 degraded2++;
 638         }
 639         rcu_read_unlock();
 640         if (degraded2 > degraded)
 641                 return degraded2;
 642         return degraded;
 643 }
 644
 645 static int has_failed(struct r5conf *conf)
 646 {
 647         int degraded;
 648
 649         if (conf->mddev->reshape_position == MaxSector)
 650                 return conf->mddev->degraded > conf->max_degraded;
 651
 652         degraded = calc_degraded(conf);
 653         if (degraded > conf->max_degraded)
 654                 return 1;
 655         return 0;
 656 }
 657
 658 static struct stripe_head *
 659 get_active_stripe(struct r5conf *conf, sector_t sector,
 660                   int previous, int noblock, int noquiesce)
 661 {
 662         struct stripe_head *sh;
 663         int hash = stripe_hash_locks_hash(sector);
 664
 665         pr_debug("get_stripe, sector %llu\n", (unsigned long long)sector);
 666
 667         spin_lock_irq(conf->hash_locks + hash);
 668
 669         do {
 670                 wait_event_lock_irq(conf->wait_for_stripe,
 671                                     conf->quiesce == 0 || noquiesce,
 672                                     *(conf->hash_locks + hash));
 673                 sh = __find_stripe(conf, sector, conf->generation - previous);
 674                 if (!sh) {
 675                         if (!test_bit(R5_INACTIVE_BLOCKED, &conf->cache_state)) {
 676                                 sh = get_free_stripe(conf, hash);
 677                                 if (!sh && llist_empty(&conf->released_stripes) &&
 678                                     !test_bit(R5_DID_ALLOC, &conf->cache_state))
 679                                         set_bit(R5_ALLOC_MORE,
 680                                                 &conf->cache_state);
 681                         }
 682                         if (noblock && sh == NULL)
 683                                 break;
 684                         if (!sh) {
 685                                 set_bit(R5_INACTIVE_BLOCKED,
 686                                         &conf->cache_state);
 687                                 wait_event_lock_irq(
 688                                         conf->wait_for_stripe,
 689                                         !list_empty(conf->inactive_list + hash) &&
 690                                         (atomic_read(&conf->active_stripes)
 691                                          < (conf->max_nr_stripes * 3 / 4)
 692                                          || !test_bit(R5_INACTIVE_BLOCKED,
 693                                                       &conf->cache_state)),
 694                                         *(conf->hash_locks + hash));
 695                                 clear_bit(R5_INACTIVE_BLOCKED,
 696                                           &conf->cache_state);
 697                         } else {
 698                                 init_stripe(sh, sector, previous);
 699                                 atomic_inc(&sh->count);
 700                         }
 701                 } else if (!atomic_inc_not_zero(&sh->count)) {
 702                         spin_lock(&conf->device_lock);
 703                         if (!atomic_read(&sh->count)) {
 704                                 if (!test_bit(STRIPE_HANDLE, &sh->state))
 705                                         atomic_inc(&conf->active_stripes);
 706                                 BUG_ON(list_empty(&sh->lru) &&
 707                                        !test_bit(STRIPE_EXPANDING, &sh->state));
 708                                 list_del_init(&sh->lru);
 709                                 if (sh->group) {
 710                                         sh->group->stripes_cnt--;
 711                                         sh->group = NULL;
 712                                 }
 713                         }
 714                         atomic_inc(&sh->count);
 715                         spin_unlock(&conf->device_lock);
 716                 }
 717         } while (sh == NULL);
 718
 719         spin_unlock_irq(conf->hash_locks + hash);
 720         return sh;
 721 }
 722
 723 static bool is_full_stripe_write(struct stripe_head *sh)
 724 {
 725         BUG_ON(sh->overwrite_disks > (sh->disks - sh->raid_conf->max_degraded));
 726         return sh->overwrite_disks == (sh->disks - sh->raid_conf->max_degraded);
 727 }
 728
 729 static void lock_two_stripes(struct stripe_head *sh1, struct stripe_head *sh2)
 730 {
 731         local_irq_disable();
 732         if (sh1 > sh2) {
 733                 spin_lock(&sh2->stripe_lock);
 734                 spin_lock_nested(&sh1->stripe_lock, 1);
 735         } else {
 736                 spin_lock(&sh1->stripe_lock);
 737                 spin_lock_nested(&sh2->stripe_lock, 1);
 738         }
 739 }
 740
 741 static void unlock_two_stripes(struct stripe_head *sh1, struct stripe_head *sh2)
 742 {
 743         spin_unlock(&sh1->stripe_lock);
 744         spin_unlock(&sh2->stripe_lock);
 745         local_irq_enable();
 746 }
 747
 748 /* Only freshly new full stripe normal write stripe can be added to a batch list */
 749 static bool stripe_can_batch(struct stripe_head *sh)
 750 {
 751         return test_bit(STRIPE_BATCH_READY, &sh->state) &&
 752                 !test_bit(STRIPE_BITMAP_PENDING, &sh->state) &&
 753                 is_full_stripe_write(sh);
 754 }
 755
 756 /* we only do back search */
 757 static void stripe_add_to_batch_list(struct r5conf *conf, struct stripe_head *sh)
 758 {
 759         struct stripe_head *head;
 760         sector_t head_sector, tmp_sec;
 761         int hash;
 762         int dd_idx;
 763
 764         if (!stripe_can_batch(sh))
 765                 return;
 766         /* Don't cross chunks, so stripe pd_idx/qd_idx is the same */
 767         tmp_sec = sh->sector;
 768         if (!sector_div(tmp_sec, conf->chunk_sectors))
 769                 return;
 770         head_sector = sh->sector - STRIPE_SECTORS;
 771
 772         hash = stripe_hash_locks_hash(head_sector);
 773         spin_lock_irq(conf->hash_locks + hash);
 774         head = __find_stripe(conf, head_sector, conf->generation);
 775         if (head && !atomic_inc_not_zero(&head->count)) {
 776                 spin_lock(&conf->device_lock);
 777                 if (!atomic_read(&head->count)) {
 778                         if (!test_bit(STRIPE_HANDLE, &head->state))
 779                                 atomic_inc(&conf->active_stripes);
 780                         BUG_ON(list_empty(&head->lru) &&
 781                                !test_bit(STRIPE_EXPANDING, &head->state));
 782                         list_del_init(&head->lru);
 783                         if (head->group) {
 784                                 head->group->stripes_cnt--;
 785                                 head->group = NULL;
 786                         }
 787                 }
 788                 atomic_inc(&head->count);
 789                 spin_unlock(&conf->device_lock);
 790         }
 791         spin_unlock_irq(conf->hash_locks + hash);
 792
 793         if (!head)
 794                 return;
 795         if (!stripe_can_batch(head))
 796                 goto out;
 797
 798         lock_two_stripes(head, sh);
 799         /* clear_batch_ready clear the flag */
 800         if (!stripe_can_batch(head) || !stripe_can_batch(sh))
 801                 goto unlock_out;
 802
 803         if (sh->batch_head)
 804                 goto unlock_out;
 805
 806         dd_idx = 0;
 807         while (dd_idx == sh->pd_idx || dd_idx == sh->qd_idx)
 808                 dd_idx++;
 809         if (head->dev[dd_idx].towrite->bi_rw != sh->dev[dd_idx].towrite->bi_rw)
 810                 goto unlock_out;
 811
 812         if (head->batch_head) {
 813                 spin_lock(&head->batch_head->batch_lock);
 814                 /* This batch list is already running */
 815                 if (!stripe_can_batch(head)) {
 816                         spin_unlock(&head->batch_head->batch_lock);
 817                         goto unlock_out;
 818                 }
 819
 820                 /*
 821                  * at this point, head's BATCH_READY could be cleared, but we
 822                  * can still add the stripe to batch list
 823                  */
 824                 list_add(&sh->batch_list, &head->batch_list);
 825                 spin_unlock(&head->batch_head->batch_lock);
 826
 827                 sh->batch_head = head->batch_head;
 828         } else {
 829                 head->batch_head = head;
 830                 sh->batch_head = head->batch_head;
 831                 spin_lock(&head->batch_lock);
 832                 list_add_tail(&sh->batch_list, &head->batch_list);
 833                 spin_unlock(&head->batch_lock);
 834         }
 835
 836         if (test_and_clear_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
 837                 if (atomic_dec_return(&conf->preread_active_stripes)
 838                     < IO_THRESHOLD)
 839                         md_wakeup_thread(conf->mddev->thread);
 840
 841         if (test_and_clear_bit(STRIPE_BIT_DELAY, &sh->state)) {
 842                 int seq = sh->bm_seq;
 843                 if (test_bit(STRIPE_BIT_DELAY, &sh->batch_head->state) &&
 844                     sh->batch_head->bm_seq > seq)
 845                         seq = sh->batch_head->bm_seq;
 846                 set_bit(STRIPE_BIT_DELAY, &sh->batch_head->state);
 847                 sh->batch_head->bm_seq = seq;
 848         }
 849
 850         atomic_inc(&sh->count);
 851 unlock_out:
 852         unlock_two_stripes(head, sh);
 853 out:
 854         release_stripe(head);
 855 }
 856
 857 /* Determine if 'data_offset' or 'new_data_offset' should be used
 858  * in this stripe_head.
 859  */
 860 static int use_new_offset(struct r5conf *conf, struct stripe_head *sh)
 861 {
 862         sector_t progress = conf->reshape_progress;
 863         /* Need a memory barrier to make sure we see the value
 864          * of conf->generation, or ->data_offset that was set before
 865          * reshape_progress was updated.
 866          */
 867         smp_rmb();
 868         if (progress == MaxSector)
 869                 return 0;
 870         if (sh->generation == conf->generation - 1)
 871                 return 0;
 872         /* We are in a reshape, and this is a new-generation stripe,
 873          * so use new_data_offset.
 874          */
 875         return 1;
 876 }
 877
 878 static void
 879 raid5_end_read_request(struct bio *bi, int error);
 880 static void
 881 raid5_end_write_request(struct bio *bi, int error);
 882
 883 static void ops_run_io(struct stripe_head *sh, struct stripe_head_state *s)
 884 {
 885         struct r5conf *conf = sh->raid_conf;
 886         int i, disks = sh->disks;
 887         struct stripe_head *head_sh = sh;
 888
 889         might_sleep();
 890
 891         for (i = disks; i--; ) {
 892                 int rw;
 893                 int replace_only = 0;
 894                 struct bio *bi, *rbi;
 895                 struct md_rdev *rdev, *rrdev = NULL;
 896
 897                 sh = head_sh;
 898                 if (test_and_clear_bit(R5_Wantwrite, &sh->dev[i].flags)) {
 899                         if (test_and_clear_bit(R5_WantFUA, &sh->dev[i].flags))
 900                                 rw = WRITE_FUA;
 901                         else
 902                                 rw = WRITE;
 903                         if (test_bit(R5_Discard, &sh->dev[i].flags))
 904                                 rw |= REQ_DISCARD;
 905                 } else if (test_and_clear_bit(R5_Wantread, &sh->dev[i].flags))
 906                         rw = READ;
 907                 else if (test_and_clear_bit(R5_WantReplace,
 908                                             &sh->dev[i].flags)) {
 909                         rw = WRITE;
 910                         replace_only = 1;
 911                 } else
 912                         continue;
 913                 if (test_and_clear_bit(R5_SyncIO, &sh->dev[i].flags))
 914                         rw |= REQ_SYNC;
 915
 916 again:
 917                 bi = &sh->dev[i].req;
 918                 rbi = &sh->dev[i].rreq; /* For writing to replacement */
 919
 920                 rcu_read_lock();
 921                 rrdev = rcu_dereference(conf->disks[i].replacement);
 922                 smp_mb(); /* Ensure that if rrdev is NULL, rdev won't be */
 923                 rdev = rcu_dereference(conf->disks[i].rdev);
 924                 if (!rdev) {
 925                         rdev = rrdev;
 926                         rrdev = NULL;
 927                 }
 928                 if (rw & WRITE) {
 929                         if (replace_only)
 930                                 rdev = NULL;
 931                         if (rdev == rrdev)
 932                                 /* We raced and saw duplicates */
 933                                 rrdev = NULL;
 934                 } else {
 935                         if (test_bit(R5_ReadRepl, &head_sh->dev[i].flags) && rrdev)
 936                                 rdev = rrdev;
 937                         rrdev = NULL;
 938                 }
 939
 940                 if (rdev && test_bit(Faulty, &rdev->flags))
 941                         rdev = NULL;
 942                 if (rdev)
 943                         atomic_inc(&rdev->nr_pending);
 944                 if (rrdev && test_bit(Faulty, &rrdev->flags))
 945                         rrdev = NULL;
 946                 if (rrdev)
 947                         atomic_inc(&rrdev->nr_pending);
 948                 rcu_read_unlock();
 949
 950                 /* We have already checked bad blocks for reads.  Now
 951                  * need to check for writes.  We never accept write errors
 952                  * on the replacement, so we don't to check rrdev.
 953                  */
 954                 while ((rw & WRITE) && rdev &&
 955                        test_bit(WriteErrorSeen, &rdev->flags)) {
 956                         sector_t first_bad;
 957                         int bad_sectors;
 958                         int bad = is_badblock(rdev, sh->sector, STRIPE_SECTORS,
 959                                               &first_bad, &bad_sectors);
 960                         if (!bad)
 961                                 break;
 962
 963                         if (bad < 0) {
 964                                 set_bit(BlockedBadBlocks, &rdev->flags);
 965                                 if (!conf->mddev->external &&
 966                                     conf->mddev->flags) {
 967                                         /* It is very unlikely, but we might
 968                                          * still need to write out the
 969                                          * bad block log - better give it
 970                                          * a chance*/
 971                                         md_check_recovery(conf->mddev);
 972                                 }
 973                                 /*
 974                                  * Because md_wait_for_blocked_rdev
 975                                  * will dec nr_pending, we must
 976                                  * increment it first.
 977                                  */
 978                                 atomic_inc(&rdev->nr_pending);
 979                                 md_wait_for_blocked_rdev(rdev, conf->mddev);
 980                         } else {
 981                                 /* Acknowledged bad block - skip the write */
 982                                 rdev_dec_pending(rdev, conf->mddev);
 983                                 rdev = NULL;
 984                         }
 985                 }
 986
 987                 if (rdev) {
 988                         if (s->syncing || s->expanding || s->expanded
 989                             || s->replacing)
 990                                 md_sync_acct(rdev->bdev, STRIPE_SECTORS);
 991
 992                         set_bit(STRIPE_IO_STARTED, &sh->state);
 993
 994                         bio_reset(bi);
 995                         bi->bi_bdev = rdev->bdev;
 996                         bi->bi_rw = rw;
 997                         bi->bi_end_io = (rw & WRITE)
 998                                 ? raid5_end_write_request
 999                                 : raid5_end_read_request;
1000                         bi->bi_private = sh;
1001
1002                         pr_debug("%s: for %llu schedule op %ld on disc %d\n",
1003                                 __func__, (unsigned long long)sh->sector,
1004                                 bi->bi_rw, i);
1005                         atomic_inc(&sh->count);
1006                         if (sh != head_sh)
1007                                 atomic_inc(&head_sh->count);
1008                         if (use_new_offset(conf, sh))
1009                                 bi->bi_iter.bi_sector = (sh->sector
1010                                                  + rdev->new_data_offset);
1011                         else
1012                                 bi->bi_iter.bi_sector = (sh->sector
1013                                                  + rdev->data_offset);
1014                         if (test_bit(R5_ReadNoMerge, &head_sh->dev[i].flags))
1015                                 bi->bi_rw |= REQ_NOMERGE;
1016
1017                         if (test_bit(R5_SkipCopy, &sh->dev[i].flags))
1018                                 WARN_ON(test_bit(R5_UPTODATE, &sh->dev[i].flags));
1019                         sh->dev[i].vec.bv_page = sh->dev[i].page;
1020                         bi->bi_vcnt = 1;
1021                         bi->bi_io_vec[0].bv_len = STRIPE_SIZE;
1022                         bi->bi_io_vec[0].bv_offset = 0;
1023                         bi->bi_iter.bi_size = STRIPE_SIZE;
1024                         /*
1025                          * If this is discard request, set bi_vcnt 0. We don't
1026                          * want to confuse SCSI because SCSI will replace payload
1027                          */
1028                         if (rw & REQ_DISCARD)
1029                                 bi->bi_vcnt = 0;
1030                         if (rrdev)
1031                                 set_bit(R5_DOUBLE_LOCKED, &sh->dev[i].flags);
1032
1033                         if (conf->mddev->gendisk)
1034                                 trace_block_bio_remap(bdev_get_queue(bi->bi_bdev),
1035                                                       bi, disk_devt(conf->mddev->gendisk),
1036                                                       sh->dev[i].sector);
1037                         generic_make_request(bi);
1038                 }
1039                 if (rrdev) {
1040                         if (s->syncing || s->expanding || s->expanded
1041                             || s->replacing)
1042                                 md_sync_acct(rrdev->bdev, STRIPE_SECTORS);
1043
1044                         set_bit(STRIPE_IO_STARTED, &sh->state);
1045
1046                         bio_reset(rbi);
1047                         rbi->bi_bdev = rrdev->bdev;
1048                         rbi->bi_rw = rw;
1049                         BUG_ON(!(rw & WRITE));
1050                         rbi->bi_end_io = raid5_end_write_request;
1051                         rbi->bi_private = sh;
1052
1053                         pr_debug("%s: for %llu schedule op %ld on "
1054                                  "replacement disc %d\n",
1055                                 __func__, (unsigned long long)sh->sector,
1056                                 rbi->bi_rw, i);
1057                         atomic_inc(&sh->count);
1058                         if (sh != head_sh)
1059                                 atomic_inc(&head_sh->count);
1060                         if (use_new_offset(conf, sh))
1061                                 rbi->bi_iter.bi_sector = (sh->sector
1062                                                   + rrdev->new_data_offset);
1063                         else
1064                                 rbi->bi_iter.bi_sector = (sh->sector
1065                                                   + rrdev->data_offset);
1066                         if (test_bit(R5_SkipCopy, &sh->dev[i].flags))
1067                                 WARN_ON(test_bit(R5_UPTODATE, &sh->dev[i].flags));
1068                         sh->dev[i].rvec.bv_page = sh->dev[i].page;
1069                         rbi->bi_vcnt = 1;
1070                         rbi->bi_io_vec[0].bv_len = STRIPE_SIZE;
1071                         rbi->bi_io_vec[0].bv_offset = 0;
1072                         rbi->bi_iter.bi_size = STRIPE_SIZE;
1073                         /*
1074                          * If this is discard request, set bi_vcnt 0. We don't
1075                          * want to confuse SCSI because SCSI will replace payload
1076                          */
1077                         if (rw & REQ_DISCARD)
1078                                 rbi->bi_vcnt = 0;
1079                         if (conf->mddev->gendisk)
1080                                 trace_block_bio_remap(bdev_get_queue(rbi->bi_bdev),
1081                                                       rbi, disk_devt(conf->mddev->gendisk),
1082                                                       sh->dev[i].sector);
1083                         generic_make_request(rbi);
1084                 }
1085                 if (!rdev && !rrdev) {
1086                         if (rw & WRITE)
1087                                 set_bit(STRIPE_DEGRADED, &sh->state);
1088                         pr_debug("skip op %ld on disc %d for sector %llu\n",
1089                                 bi->bi_rw, i, (unsigned long long)sh->sector);
1090                         clear_bit(R5_LOCKED, &sh->dev[i].flags);
1091                         set_bit(STRIPE_HANDLE, &sh->state);
1092                 }
1093
1094                 if (!head_sh->batch_head)
1095                         continue;
1096                 sh = list_first_entry(&sh->batch_list, struct stripe_head,
1097                                       batch_list);
1098                 if (sh != head_sh)
1099                         goto again;
1100         }
1101 }
1102
1103 static struct dma_async_tx_descriptor *
1104 async_copy_data(int frombio, struct bio *bio, struct page **page,
1105         sector_t sector, struct dma_async_tx_descriptor *tx,
1106         struct stripe_head *sh)
1107 {
1108         struct bio_vec bvl;
1109         struct bvec_iter iter;
1110         struct page *bio_page;
1111         int page_offset;
1112         struct async_submit_ctl submit;
1113         enum async_tx_flags flags = 0;
1114
1115         if (bio->bi_iter.bi_sector >= sector)
1116                 page_offset = (signed)(bio->bi_iter.bi_sector - sector) * 512;
1117         else
1118                 page_offset = (signed)(sector - bio->bi_iter.bi_sector) * -512;
1119
1120         if (frombio)
1121                 flags |= ASYNC_TX_FENCE;
1122         init_async_submit(&submit, flags, tx, NULL, NULL, NULL);
1123
1124         bio_for_each_segment(bvl, bio, iter) {
1125                 int len = bvl.bv_len;
1126                 int clen;
1127                 int b_offset = 0;
1128
1129                 if (page_offset < 0) {
1130                         b_offset = -page_offset;
1131                         page_offset += b_offset;
1132                         len -= b_offset;
1133                 }
1134
1135                 if (len > 0 && page_offset + len > STRIPE_SIZE)
1136                         clen = STRIPE_SIZE - page_offset;
1137                 else
1138                         clen = len;
1139
1140                 if (clen > 0) {
1141                         b_offset += bvl.bv_offset;
1142                         bio_page = bvl.bv_page;
1143                         if (frombio) {
1144                                 if (sh->raid_conf->skip_copy &&
1145                                     b_offset == 0 && page_offset == 0 &&
1146                                     clen == STRIPE_SIZE)
1147                                         *page = bio_page;
1148                                 else
1149                                         tx = async_memcpy(*page, bio_page, page_offset,
1150                                                   b_offset, clen, &submit);
1151                         } else
1152                                 tx = async_memcpy(bio_page, *page, b_offset,
1153                                                   page_offset, clen, &submit);
1154                 }
1155                 /* chain the operations */
1156                 submit.depend_tx = tx;
1157
1158                 if (clen < len) /* hit end of page */
1159                         break;
1160                 page_offset +=  len;
1161         }
1162
1163         return tx;
1164 }
1165
1166 static void ops_complete_biofill(void *stripe_head_ref)
1167 {
1168         struct stripe_head *sh = stripe_head_ref;
1169         struct bio *return_bi = NULL;
1170         int i;
1171
1172         pr_debug("%s: stripe %llu\n", __func__,
1173                 (unsigned long long)sh->sector);
1174
1175         /* clear completed biofills */
1176         for (i = sh->disks; i--; ) {
1177                 struct r5dev *dev = &sh->dev[i];
1178
1179                 /* acknowledge completion of a biofill operation */
1180                 /* and check if we need to reply to a read request,
1181                  * new R5_Wantfill requests are held off until
1182                  * !STRIPE_BIOFILL_RUN
1183                  */
1184                 if (test_and_clear_bit(R5_Wantfill, &dev->flags)) {
1185                         struct bio *rbi, *rbi2;
1186
1187                         BUG_ON(!dev->read);
1188                         rbi = dev->read;
1189                         dev->read = NULL;
1190                         while (rbi && rbi->bi_iter.bi_sector <
1191                                 dev->sector + STRIPE_SECTORS) {
1192                                 rbi2 = r5_next_bio(rbi, dev->sector);
1193                                 if (!raid5_dec_bi_active_stripes(rbi)) {
1194                                         rbi->bi_next = return_bi;
1195                                         return_bi = rbi;
1196                                 }
1197                                 rbi = rbi2;
1198                         }
1199                 }
1200         }
1201         clear_bit(STRIPE_BIOFILL_RUN, &sh->state);
1202
1203         return_io(return_bi);
1204
1205         set_bit(STRIPE_HANDLE, &sh->state);
1206         release_stripe(sh);
1207 }
1208
1209 static void ops_run_biofill(struct stripe_head *sh)
1210 {
1211         struct dma_async_tx_descriptor *tx = NULL;
1212         struct async_submit_ctl submit;
1213         int i;
1214
1215         BUG_ON(sh->batch_head);
1216         pr_debug("%s: stripe %llu\n", __func__,
1217                 (unsigned long long)sh->sector);
1218
1219         for (i = sh->disks; i--; ) {
1220                 struct r5dev *dev = &sh->dev[i];
1221                 if (test_bit(R5_Wantfill, &dev->flags)) {
1222                         struct bio *rbi;
1223                         spin_lock_irq(&sh->stripe_lock);
1224                         dev->read = rbi = dev->toread;
1225                         dev->toread = NULL;
1226                         spin_unlock_irq(&sh->stripe_lock);
1227                         while (rbi && rbi->bi_iter.bi_sector <
1228                                 dev->sector + STRIPE_SECTORS) {
1229                                 tx = async_copy_data(0, rbi, &dev->page,
1230                                         dev->sector, tx, sh);
1231                                 rbi = r5_next_bio(rbi, dev->sector);
1232                         }
1233                 }
1234         }
1235
1236         atomic_inc(&sh->count);
1237         init_async_submit(&submit, ASYNC_TX_ACK, tx, ops_complete_biofill, sh, NULL);
1238         async_trigger_callback(&submit);
1239 }
1240
1241 static void mark_target_uptodate(struct stripe_head *sh, int target)
1242 {
1243         struct r5dev *tgt;
1244
1245         if (target < 0)
1246                 return;
1247
1248         tgt = &sh->dev[target];
1249         set_bit(R5_UPTODATE, &tgt->flags);
1250         BUG_ON(!test_bit(R5_Wantcompute, &tgt->flags));
1251         clear_bit(R5_Wantcompute, &tgt->flags);
1252 }
1253
1254 static void ops_complete_compute(void *stripe_head_ref)
1255 {
1256         struct stripe_head *sh = stripe_head_ref;
1257
1258         pr_debug("%s: stripe %llu\n", __func__,
1259                 (unsigned long long)sh->sector);
1260
1261         /* mark the computed target(s) as uptodate */
1262         mark_target_uptodate(sh, sh->ops.target);
1263         mark_target_uptodate(sh, sh->ops.target2);
1264
1265         clear_bit(STRIPE_COMPUTE_RUN, &sh->state);
1266         if (sh->check_state == check_state_compute_run)
1267                 sh->check_state = check_state_compute_result;
1268         set_bit(STRIPE_HANDLE, &sh->state);
1269         release_stripe(sh);
1270 }
1271
1272 /* return a pointer to the address conversion region of the scribble buffer */
1273 static addr_conv_t *to_addr_conv(struct stripe_head *sh,
1274                                  struct raid5_percpu *percpu, int i)
1275 {
1276         void *addr;
1277
1278         addr = flex_array_get(percpu->scribble, i);
1279         return addr + sizeof(struct page *) * (sh->disks + 2);
1280 }
1281
1282 /* return a pointer to the address conversion region of the scribble buffer */
1283 static struct page **to_addr_page(struct raid5_percpu *percpu, int i)
1284 {
1285         void *addr;
1286
1287         addr = flex_array_get(percpu->scribble, i);
1288         return addr;
1289 }
1290
1291 static struct dma_async_tx_descriptor *
1292 ops_run_compute5(struct stripe_head *sh, struct raid5_percpu *percpu)
1293 {
1294         int disks = sh->disks;
1295         struct page **xor_srcs = to_addr_page(percpu, 0);
1296         int target = sh->ops.target;
1297         struct r5dev *tgt = &sh->dev[target];
1298         struct page *xor_dest = tgt->page;
1299         int count = 0;
1300         struct dma_async_tx_descriptor *tx;
1301         struct async_submit_ctl submit;
1302         int i;
1303
1304         BUG_ON(sh->batch_head);
1305
1306         pr_debug("%s: stripe %llu block: %d\n",
1307                 __func__, (unsigned long long)sh->sector, target);
1308         BUG_ON(!test_bit(R5_Wantcompute, &tgt->flags));
1309
1310         for (i = disks; i--; )
1311                 if (i != target)
1312                         xor_srcs[count++] = sh->dev[i].page;
1313
1314         atomic_inc(&sh->count);
1315
1316         init_async_submit(&submit, ASYNC_TX_FENCE|ASYNC_TX_XOR_ZERO_DST, NULL,
1317                           ops_complete_compute, sh, to_addr_conv(sh, percpu, 0));
1318         if (unlikely(count == 1))
1319                 tx = async_memcpy(xor_dest, xor_srcs[0], 0, 0, STRIPE_SIZE, &submit);
1320         else
1321                 tx = async_xor(xor_dest, xor_srcs, 0, count, STRIPE_SIZE, &submit);
1322
1323         return tx;
1324 }
1325
1326 /* set_syndrome_sources - populate source buffers for gen_syndrome
1327  * @srcs - (struct page *) array of size sh->disks
1328  * @sh - stripe_head to parse
1329  *
1330  * Populates srcs in proper layout order for the stripe and returns the
1331  * 'count' of sources to be used in a call to async_gen_syndrome.  The P
1332  * destination buffer is recorded in srcs[count] and the Q destination
1333  * is recorded in srcs[count+1]].
1334  */
1335 static int set_syndrome_sources(struct page **srcs,
1336                                 struct stripe_head *sh,
1337                                 int srctype)
1338 {
1339         int disks = sh->disks;
1340         int syndrome_disks = sh->ddf_layout ? disks : (disks - 2);
1341         int d0_idx = raid6_d0(sh);
1342         int count;
1343         int i;
1344
1345         for (i = 0; i < disks; i++)
1346                 srcs[i] = NULL;
1347
1348         count = 0;
1349         i = d0_idx;
1350         do {
1351                 int slot = raid6_idx_to_slot(i, sh, &count, syndrome_disks);
1352                 struct r5dev *dev = &sh->dev[i];
1353
1354                 if (i == sh->qd_idx || i == sh->pd_idx ||
1355                     (srctype == SYNDROME_SRC_ALL) ||
1356                     (srctype == SYNDROME_SRC_WANT_DRAIN &&
1357                      test_bit(R5_Wantdrain, &dev->flags)) ||
1358                     (srctype == SYNDROME_SRC_WRITTEN &&
1359                      dev->written))
1360                         srcs[slot] = sh->dev[i].page;
1361                 i = raid6_next_disk(i, disks);
1362         } while (i != d0_idx);
1363
1364         return syndrome_disks;
1365 }
1366
1367 static struct dma_async_tx_descriptor *
1368 ops_run_compute6_1(struct stripe_head *sh, struct raid5_percpu *percpu)
1369 {
1370         int disks = sh->disks;
1371         struct page **blocks = to_addr_page(percpu, 0);
1372         int target;
1373         int qd_idx = sh->qd_idx;
1374         struct dma_async_tx_descriptor *tx;
1375         struct async_submit_ctl submit;
1376         struct r5dev *tgt;
1377         struct page *dest;
1378         int i;
1379         int count;
1380
1381         BUG_ON(sh->batch_head);
1382         if (sh->ops.target < 0)
1383                 target = sh->ops.target2;
1384         else if (sh->ops.target2 < 0)
1385                 target = sh->ops.target;
1386         else
1387                 /* we should only have one valid target */
1388                 BUG();
1389         BUG_ON(target < 0);
1390         pr_debug("%s: stripe %llu block: %d\n",
1391                 __func__, (unsigned long long)sh->sector, target);
1392
1393         tgt = &sh->dev[target];
1394         BUG_ON(!test_bit(R5_Wantcompute, &tgt->flags));
1395         dest = tgt->page;
1396
1397         atomic_inc(&sh->count);
1398
1399         if (target == qd_idx) {
1400                 count = set_syndrome_sources(blocks, sh, SYNDROME_SRC_ALL);
1401                 blocks[count] = NULL; /* regenerating p is not necessary */
1402                 BUG_ON(blocks[count+1] != dest); /* q should already be set */
1403                 init_async_submit(&submit, ASYNC_TX_FENCE, NULL,
1404                                   ops_complete_compute, sh,
1405                                   to_addr_conv(sh, percpu, 0));
1406                 tx = async_gen_syndrome(blocks, 0, count+2, STRIPE_SIZE, &submit);
1407         } else {
1408                 /* Compute any data- or p-drive using XOR */
1409                 count = 0;
1410                 for (i = disks; i-- ; ) {
1411                         if (i == target || i == qd_idx)
1412                                 continue;
1413                         blocks[count++] = sh->dev[i].page;
1414                 }
1415
1416                 init_async_submit(&submit, ASYNC_TX_FENCE|ASYNC_TX_XOR_ZERO_DST,
1417                                   NULL, ops_complete_compute, sh,
1418                                   to_addr_conv(sh, percpu, 0));
1419                 tx = async_xor(dest, blocks, 0, count, STRIPE_SIZE, &submit);
1420         }
1421
1422         return tx;
1423 }
1424
1425 static struct dma_async_tx_descriptor *
1426 ops_run_compute6_2(struct stripe_head *sh, struct raid5_percpu *percpu)
1427 {
1428         int i, count, disks = sh->disks;
1429         int syndrome_disks = sh->ddf_layout ? disks : disks-2;
1430         int d0_idx = raid6_d0(sh);
1431         int faila = -1, failb = -1;
1432         int target = sh->ops.target;
1433         int target2 = sh->ops.target2;
1434         struct r5dev *tgt = &sh->dev[target];
1435         struct r5dev *tgt2 = &sh->dev[target2];
1436         struct dma_async_tx_descriptor *tx;
1437         struct page **blocks = to_addr_page(percpu, 0);
1438         struct async_submit_ctl submit;
1439
1440         BUG_ON(sh->batch_head);
1441         pr_debug("%s: stripe %llu block1: %d block2: %d\n",
1442                  __func__, (unsigned long long)sh->sector, target, target2);
1443         BUG_ON(target < 0 || target2 < 0);
1444         BUG_ON(!test_bit(R5_Wantcompute, &tgt->flags));
1445         BUG_ON(!test_bit(R5_Wantcompute, &tgt2->flags));
1446
1447         /* we need to open-code set_syndrome_sources to handle the
1448          * slot number conversion for 'faila' and 'failb'
1449          */
1450         for (i = 0; i < disks ; i++)
1451                 blocks[i] = NULL;
1452         count = 0;
1453         i = d0_idx;
1454         do {
1455                 int slot = raid6_idx_to_slot(i, sh, &count, syndrome_disks);
1456
1457                 blocks[slot] = sh->dev[i].page;
1458
1459                 if (i == target)
1460                         faila = slot;
1461                 if (i == target2)
1462                         failb = slot;
1463                 i = raid6_next_disk(i, disks);
1464         } while (i != d0_idx);
1465
1466         BUG_ON(faila == failb);
1467         if (failb < faila)
1468                 swap(faila, failb);
1469         pr_debug("%s: stripe: %llu faila: %d failb: %d\n",
1470                  __func__, (unsigned long long)sh->sector, faila, failb);
1471
1472         atomic_inc(&sh->count);
1473
1474         if (failb == syndrome_disks+1) {
1475                 /* Q disk is one of the missing disks */
1476                 if (faila == syndrome_disks) {
1477                         /* Missing P+Q, just recompute */
1478                         init_async_submit(&submit, ASYNC_TX_FENCE, NULL,
1479                                           ops_complete_compute, sh,
1480                                           to_addr_conv(sh, percpu, 0));
1481                         return async_gen_syndrome(blocks, 0, syndrome_disks+2,
1482                                                   STRIPE_SIZE, &submit);
1483                 } else {
1484                         struct page *dest;
1485                         int data_target;
1486                         int qd_idx = sh->qd_idx;
1487
1488                         /* Missing D+Q: recompute D from P, then recompute Q */
1489                         if (target == qd_idx)
1490                                 data_target = target2;
1491                         else
1492                                 data_target = target;
1493
1494                         count = 0;
1495                         for (i = disks; i-- ; ) {
1496                                 if (i == data_target || i == qd_idx)
1497                                         continue;
1498                                 blocks[count++] = sh->dev[i].page;
1499                         }
1500                         dest = sh->dev[data_target].page;
1501                         init_async_submit(&submit,
1502                                           ASYNC_TX_FENCE|ASYNC_TX_XOR_ZERO_DST,
1503                                           NULL, NULL, NULL,
1504                                           to_addr_conv(sh, percpu, 0));
1505                         tx = async_xor(dest, blocks, 0, count, STRIPE_SIZE,
1506                                        &submit);
1507
1508                         count = set_syndrome_sources(blocks, sh, SYNDROME_SRC_ALL);
1509                         init_async_submit(&submit, ASYNC_TX_FENCE, tx,
1510                                           ops_complete_compute, sh,
1511                                           to_addr_conv(sh, percpu, 0));
1512                         return async_gen_syndrome(blocks, 0, count+2,
1513                                                   STRIPE_SIZE, &submit);
1514                 }
1515         } else {
1516                 init_async_submit(&submit, ASYNC_TX_FENCE, NULL,
1517                                   ops_complete_compute, sh,
1518                                   to_addr_conv(sh, percpu, 0));
1519                 if (failb == syndrome_disks) {
1520                         /* We're missing D+P. */
1521                         return async_raid6_datap_recov(syndrome_disks+2,
1522                                                        STRIPE_SIZE, faila,
1523                                                        blocks, &submit);
1524                 } else {
1525                         /* We're missing D+D. */
1526                         return async_raid6_2data_recov(syndrome_disks+2,
1527                                                        STRIPE_SIZE, faila, failb,
1528                                                        blocks, &submit);
1529                 }
1530         }
1531 }
1532
1533 static void ops_complete_prexor(void *stripe_head_ref)
1534 {
1535         struct stripe_head *sh = stripe_head_ref;
1536
1537         pr_debug("%s: stripe %llu\n", __func__,
1538                 (unsigned long long)sh->sector);
1539 }
1540
1541 static struct dma_async_tx_descriptor *
1542 ops_run_prexor5(struct stripe_head *sh, struct raid5_percpu *percpu,
1543                 struct dma_async_tx_descriptor *tx)
1544 {
1545         int disks = sh->disks;
1546         struct page **xor_srcs = to_addr_page(percpu, 0);
1547         int count = 0, pd_idx = sh->pd_idx, i;
1548         struct async_submit_ctl submit;
1549
1550         /* existing parity data subtracted */
1551         struct page *xor_dest = xor_srcs[count++] = sh->dev[pd_idx].page;
1552
1553         BUG_ON(sh->batch_head);
1554         pr_debug("%s: stripe %llu\n", __func__,
1555                 (unsigned long long)sh->sector);
1556
1557         for (i = disks; i--; ) {
1558                 struct r5dev *dev = &sh->dev[i];
1559                 /* Only process blocks that are known to be uptodate */
1560                 if (test_bit(R5_Wantdrain, &dev->flags))
1561                         xor_srcs[count++] = dev->page;
1562         }
1563
1564         init_async_submit(&submit, ASYNC_TX_FENCE|ASYNC_TX_XOR_DROP_DST, tx,
1565                           ops_complete_prexor, sh, to_addr_conv(sh, percpu, 0));
1566         tx = async_xor(xor_dest, xor_srcs, 0, count, STRIPE_SIZE, &submit);
1567
1568         return tx;
1569 }
1570
1571 static struct dma_async_tx_descriptor *
1572 ops_run_prexor6(struct stripe_head *sh, struct raid5_percpu *percpu,
1573                 struct dma_async_tx_descriptor *tx)
1574 {
1575         struct page **blocks = to_addr_page(percpu, 0);
1576         int count;
1577         struct async_submit_ctl submit;
1578
1579         pr_debug("%s: stripe %llu\n", __func__,
1580                 (unsigned long long)sh->sector);
1581
1582         count = set_syndrome_sources(blocks, sh, SYNDROME_SRC_WANT_DRAIN);
1583
1584         init_async_submit(&submit, ASYNC_TX_FENCE|ASYNC_TX_PQ_XOR_DST, tx,
1585                           ops_complete_prexor, sh, to_addr_conv(sh, percpu, 0));
1586         tx = async_gen_syndrome(blocks, 0, count+2, STRIPE_SIZE,  &submit);
1587
1588         return tx;
1589 }
1590
1591 static struct dma_async_tx_descriptor *
1592 ops_run_biodrain(struct stripe_head *sh, struct dma_async_tx_descriptor *tx)
1593 {
1594         int disks = sh->disks;
1595         int i;
1596         struct stripe_head *head_sh = sh;
1597
1598         pr_debug("%s: stripe %llu\n", __func__,
1599                 (unsigned long long)sh->sector);
1600
1601         for (i = disks; i--; ) {
1602                 struct r5dev *dev;
1603                 struct bio *chosen;
1604
1605                 sh = head_sh;
1606                 if (test_and_clear_bit(R5_Wantdrain, &head_sh->dev[i].flags)) {
1607                         struct bio *wbi;
1608
1609 again:
1610                         dev = &sh->dev[i];
1611                         spin_lock_irq(&sh->stripe_lock);
1612                         chosen = dev->towrite;
1613                         dev->towrite = NULL;
1614                         sh->overwrite_disks = 0;
1615                         BUG_ON(dev->written);
1616                         wbi = dev->written = chosen;
1617                         spin_unlock_irq(&sh->stripe_lock);
1618                         WARN_ON(dev->page != dev->orig_page);
1619
1620                         while (wbi && wbi->bi_iter.bi_sector <
1621                                 dev->sector + STRIPE_SECTORS) {
1622                                 if (wbi->bi_rw & REQ_FUA)
1623                                         set_bit(R5_WantFUA, &dev->flags);
1624                                 if (wbi->bi_rw & REQ_SYNC)
1625                                         set_bit(R5_SyncIO, &dev->flags);
1626                                 if (wbi->bi_rw & REQ_DISCARD)
1627                                         set_bit(R5_Discard, &dev->flags);
1628                                 else {
1629                                         tx = async_copy_data(1, wbi, &dev->page,
1630                                                 dev->sector, tx, sh);
1631                                         if (dev->page != dev->orig_page) {
1632                                                 set_bit(R5_SkipCopy, &dev->flags);
1633                                                 clear_bit(R5_UPTODATE, &dev->flags);
1634                                                 clear_bit(R5_OVERWRITE, &dev->flags);
1635                                         }
1636                                 }
1637                                 wbi = r5_next_bio(wbi, dev->sector);
1638                         }
1639
1640                         if (head_sh->batch_head) {
1641                                 sh = list_first_entry(&sh->batch_list,
1642                                                       struct stripe_head,
1643                                                       batch_list);
1644                                 if (sh == head_sh)
1645                                         continue;
1646                                 goto again;
1647                         }
1648                 }
1649         }
1650
1651         return tx;
1652 }
1653
1654 static void ops_complete_reconstruct(void *stripe_head_ref)
1655 {
1656         struct stripe_head *sh = stripe_head_ref;
1657         int disks = sh->disks;
1658         int pd_idx = sh->pd_idx;
1659         int qd_idx = sh->qd_idx;
1660         int i;
1661         bool fua = false, sync = false, discard = false;
1662
1663         pr_debug("%s: stripe %llu\n", __func__,
1664                 (unsigned long long)sh->sector);
1665
1666         for (i = disks; i--; ) {
1667                 fua |= test_bit(R5_WantFUA, &sh->dev[i].flags);
1668                 sync |= test_bit(R5_SyncIO, &sh->dev[i].flags);
1669                 discard |= test_bit(R5_Discard, &sh->dev[i].flags);
1670         }
1671
1672         for (i = disks; i--; ) {
1673                 struct r5dev *dev = &sh->dev[i];
1674
1675                 if (dev->written || i == pd_idx || i == qd_idx) {
1676                         if (!discard && !test_bit(R5_SkipCopy, &dev->flags))
1677                                 set_bit(R5_UPTODATE, &dev->flags);
1678                         if (fua)
1679                                 set_bit(R5_WantFUA, &dev->flags);
1680                         if (sync)
1681                                 set_bit(R5_SyncIO, &dev->flags);
1682                 }
1683         }
1684
1685         if (sh->reconstruct_state == reconstruct_state_drain_run)
1686                 sh->reconstruct_state = reconstruct_state_drain_result;
1687         else if (sh->reconstruct_state == reconstruct_state_prexor_drain_run)
1688                 sh->reconstruct_state = reconstruct_state_prexor_drain_result;
1689         else {
1690                 BUG_ON(sh->reconstruct_state != reconstruct_state_run);
1691                 sh->reconstruct_state = reconstruct_state_result;
1692         }
1693
1694         set_bit(STRIPE_HANDLE, &sh->state);
1695         release_stripe(sh);
1696 }
1697
1698 static void
1699 ops_run_reconstruct5(struct stripe_head *sh, struct raid5_percpu *percpu,
1700                      struct dma_async_tx_descriptor *tx)
1701 {
1702         int disks = sh->disks;
1703         struct page **xor_srcs;
1704         struct async_submit_ctl submit;
1705         int count, pd_idx = sh->pd_idx, i;
1706         struct page *xor_dest;
1707         int prexor = 0;
1708         unsigned long flags;
1709         int j = 0;
1710         struct stripe_head *head_sh = sh;
1711         int last_stripe;
1712
1713         pr_debug("%s: stripe %llu\n", __func__,
1714                 (unsigned long long)sh->sector);
1715
1716         for (i = 0; i < sh->disks; i++) {
1717                 if (pd_idx == i)
1718                         continue;
1719                 if (!test_bit(R5_Discard, &sh->dev[i].flags))
1720                         break;
1721         }
1722         if (i >= sh->disks) {
1723                 atomic_inc(&sh->count);
1724                 set_bit(R5_Discard, &sh->dev[pd_idx].flags);
1725                 ops_complete_reconstruct(sh);
1726                 return;
1727         }
1728 again:
1729         count = 0;
1730         xor_srcs = to_addr_page(percpu, j);
1731         /* check if prexor is active which means only process blocks
1732          * that are part of a read-modify-write (written)
1733          */
1734         if (head_sh->reconstruct_state == reconstruct_state_prexor_drain_run) {
1735                 prexor = 1;
1736                 xor_dest = xor_srcs[count++] = sh->dev[pd_idx].page;
1737                 for (i = disks; i--; ) {
1738                         struct r5dev *dev = &sh->dev[i];
1739                         if (head_sh->dev[i].written)
1740                                 xor_srcs[count++] = dev->page;
1741                 }
1742         } else {
1743                 xor_dest = sh->dev[pd_idx].page;
1744                 for (i = disks; i--; ) {
1745                         struct r5dev *dev = &sh->dev[i];
1746                         if (i != pd_idx)
1747                                 xor_srcs[count++] = dev->page;
1748                 }
1749         }
1750
1751         /* 1/ if we prexor'd then the dest is reused as a source
1752          * 2/ if we did not prexor then we are redoing the parity
1753          * set ASYNC_TX_XOR_DROP_DST and ASYNC_TX_XOR_ZERO_DST
1754          * for the synchronous xor case
1755          */
1756         last_stripe = !head_sh->batch_head ||
1757                 list_first_entry(&sh->batch_list,
1758                                  struct stripe_head, batch_list) == head_sh;
1759         if (last_stripe) {
1760                 flags = ASYNC_TX_ACK |
1761                         (prexor ? ASYNC_TX_XOR_DROP_DST : ASYNC_TX_XOR_ZERO_DST);
1762
1763                 atomic_inc(&head_sh->count);
1764                 init_async_submit(&submit, flags, tx, ops_complete_reconstruct, head_sh,
1765                                   to_addr_conv(sh, percpu, j));
1766         } else {
1767                 flags = prexor ? ASYNC_TX_XOR_DROP_DST : ASYNC_TX_XOR_ZERO_DST;
1768                 init_async_submit(&submit, flags, tx, NULL, NULL,
1769                                   to_addr_conv(sh, percpu, j));
1770         }
1771
1772         if (unlikely(count == 1))
1773                 tx = async_memcpy(xor_dest, xor_srcs[0], 0, 0, STRIPE_SIZE, &submit);
1774         else
1775                 tx = async_xor(xor_dest, xor_srcs, 0, count, STRIPE_SIZE, &submit);
1776         if (!last_stripe) {
1777                 j++;
1778                 sh = list_first_entry(&sh->batch_list, struct stripe_head,
1779                                       batch_list);
1780                 goto again;
1781         }
1782 }
1783
1784 static void
1785 ops_run_reconstruct6(struct stripe_head *sh, struct raid5_percpu *percpu,
1786                      struct dma_async_tx_descriptor *tx)
1787 {
1788         struct async_submit_ctl submit;
1789         struct page **blocks;
1790         int count, i, j = 0;
1791         struct stripe_head *head_sh = sh;
1792         int last_stripe;
1793         int synflags;
1794         unsigned long txflags;
1795
1796         pr_debug("%s: stripe %llu\n", __func__, (unsigned long long)sh->sector);
1797
1798         for (i = 0; i < sh->disks; i++) {
1799                 if (sh->pd_idx == i || sh->qd_idx == i)
1800                         continue;
1801                 if (!test_bit(R5_Discard, &sh->dev[i].flags))
1802                         break;
1803         }
1804         if (i >= sh->disks) {
1805                 atomic_inc(&sh->count);
1806                 set_bit(R5_Discard, &sh->dev[sh->pd_idx].flags);
1807                 set_bit(R5_Discard, &sh->dev[sh->qd_idx].flags);
1808                 ops_complete_reconstruct(sh);
1809                 return;
1810         }
1811
1812 again:
1813         blocks = to_addr_page(percpu, j);
1814
1815         if (sh->reconstruct_state == reconstruct_state_prexor_drain_run) {
1816                 synflags = SYNDROME_SRC_WRITTEN;
1817                 txflags = ASYNC_TX_ACK | ASYNC_TX_PQ_XOR_DST;
1818         } else {
1819                 synflags = SYNDROME_SRC_ALL;
1820                 txflags = ASYNC_TX_ACK;
1821         }
1822
1823         count = set_syndrome_sources(blocks, sh, synflags);
1824         last_stripe = !head_sh->batch_head ||
1825                 list_first_entry(&sh->batch_list,
1826                                  struct stripe_head, batch_list) == head_sh;
1827
1828         if (last_stripe) {
1829                 atomic_inc(&head_sh->count);
1830                 init_async_submit(&submit, txflags, tx, ops_complete_reconstruct,
1831                                   head_sh, to_addr_conv(sh, percpu, j));
1832         } else
1833                 init_async_submit(&submit, 0, tx, NULL, NULL,
1834                                   to_addr_conv(sh, percpu, j));
1835         tx = async_gen_syndrome(blocks, 0, count+2, STRIPE_SIZE,  &submit);
1836         if (!last_stripe) {
1837                 j++;
1838                 sh = list_first_entry(&sh->batch_list, struct stripe_head,
1839                                       batch_list);
1840                 goto again;
1841         }
1842 }
1843
1844 static void ops_complete_check(void *stripe_head_ref)
1845 {
1846         struct stripe_head *sh = stripe_head_ref;
1847
1848         pr_debug("%s: stripe %llu\n", __func__,
1849                 (unsigned long long)sh->sector);
1850
1851         sh->check_state = check_state_check_result;
1852         set_bit(STRIPE_HANDLE, &sh->state);
1853         release_stripe(sh);
1854 }
1855
1856 static void ops_run_check_p(struct stripe_head *sh, struct raid5_percpu *percpu)
1857 {
1858         int disks = sh->disks;
1859         int pd_idx = sh->pd_idx;
1860         int qd_idx = sh->qd_idx;
1861         struct page *xor_dest;
1862         struct page **xor_srcs = to_addr_page(percpu, 0);
1863         struct dma_async_tx_descriptor *tx;
1864         struct async_submit_ctl submit;
1865         int count;
1866         int i;
1867
1868         pr_debug("%s: stripe %llu\n", __func__,
1869                 (unsigned long long)sh->sector);
1870
1871         BUG_ON(sh->batch_head);
1872         count = 0;
1873         xor_dest = sh->dev[pd_idx].page;
1874         xor_srcs[count++] = xor_dest;
1875         for (i = disks; i--; ) {
1876                 if (i == pd_idx || i == qd_idx)
1877                         continue;
1878                 xor_srcs[count++] = sh->dev[i].page;
1879         }
1880
1881         init_async_submit(&submit, 0, NULL, NULL, NULL,
1882                           to_addr_conv(sh, percpu, 0));
1883         tx = async_xor_val(xor_dest, xor_srcs, 0, count, STRIPE_SIZE,
1884                            &sh->ops.zero_sum_result, &submit);
1885
1886         atomic_inc(&sh->count);
1887         init_async_submit(&submit, ASYNC_TX_ACK, tx, ops_complete_check, sh, NULL);
1888         tx = async_trigger_callback(&submit);
1889 }
1890
1891 static void ops_run_check_pq(struct stripe_head *sh, struct raid5_percpu *percpu, int checkp)
1892 {
1893         struct page **srcs = to_addr_page(percpu, 0);
1894         struct async_submit_ctl submit;
1895         int count;
1896
1897         pr_debug("%s: stripe %llu checkp: %d\n", __func__,
1898                 (unsigned long long)sh->sector, checkp);
1899
1900         BUG_ON(sh->batch_head);
1901         count = set_syndrome_sources(srcs, sh, SYNDROME_SRC_ALL);
1902         if (!checkp)
1903                 srcs[count] = NULL;
1904
1905         atomic_inc(&sh->count);
1906         init_async_submit(&submit, ASYNC_TX_ACK, NULL, ops_complete_check,
1907                           sh, to_addr_conv(sh, percpu, 0));
1908         async_syndrome_val(srcs, 0, count+2, STRIPE_SIZE,
1909                            &sh->ops.zero_sum_result, percpu->spare_page, &submit);
1910 }
1911
1912 static void raid_run_ops(struct stripe_head *sh, unsigned long ops_request)
1913 {
1914         int overlap_clear = 0, i, disks = sh->disks;
1915         struct dma_async_tx_descriptor *tx = NULL;
1916         struct r5conf *conf = sh->raid_conf;
1917         int level = conf->level;
1918         struct raid5_percpu *percpu;
1919         unsigned long cpu;
1920
1921         cpu = get_cpu_light();
1922         percpu = per_cpu_ptr(conf->percpu, cpu);
1923         spin_lock(&percpu->lock);
1924         if (test_bit(STRIPE_OP_BIOFILL, &ops_request)) {
1925                 ops_run_biofill(sh);
1926                 overlap_clear++;
1927         }
1928
1929         if (test_bit(STRIPE_OP_COMPUTE_BLK, &ops_request)) {
1930                 if (level < 6)
1931                         tx = ops_run_compute5(sh, percpu);
1932                 else {
1933                         if (sh->ops.target2 < 0 || sh->ops.target < 0)
1934                                 tx = ops_run_compute6_1(sh, percpu);
1935                         else
1936                                 tx = ops_run_compute6_2(sh, percpu);
1937                 }
1938                 /* terminate the chain if reconstruct is not set to be run */
1939                 if (tx && !test_bit(STRIPE_OP_RECONSTRUCT, &ops_request))
1940                         async_tx_ack(tx);
1941         }
1942
1943         if (test_bit(STRIPE_OP_PREXOR, &ops_request)) {
1944                 if (level < 6)
1945                         tx = ops_run_prexor5(sh, percpu, tx);
1946                 else
1947                         tx = ops_run_prexor6(sh, percpu, tx);
1948         }
1949
1950         if (test_bit(STRIPE_OP_BIODRAIN, &ops_request)) {
1951                 tx = ops_run_biodrain(sh, tx);
1952                 overlap_clear++;
1953         }
1954
1955         if (test_bit(STRIPE_OP_RECONSTRUCT, &ops_request)) {
1956                 if (level < 6)
1957                         ops_run_reconstruct5(sh, percpu, tx);
1958                 else
1959                         ops_run_reconstruct6(sh, percpu, tx);
1960         }
1961
1962         if (test_bit(STRIPE_OP_CHECK, &ops_request)) {
1963                 if (sh->check_state == check_state_run)
1964                         ops_run_check_p(sh, percpu);
1965                 else if (sh->check_state == check_state_run_q)
1966                         ops_run_check_pq(sh, percpu, 0);
1967                 else if (sh->check_state == check_state_run_pq)
1968                         ops_run_check_pq(sh, percpu, 1);
1969                 else
1970                         BUG();
1971         }
1972
1973         if (overlap_clear && !sh->batch_head)
1974                 for (i = disks; i--; ) {
1975                         struct r5dev *dev = &sh->dev[i];
1976                         if (test_and_clear_bit(R5_Overlap, &dev->flags))
1977                                 wake_up(&sh->raid_conf->wait_for_overlap);
1978                 }
1979         spin_unlock(&percpu->lock);
1980         put_cpu_light();
1981 }
1982
1983 static struct stripe_head *alloc_stripe(struct kmem_cache *sc, gfp_t gfp)
1984 {
1985         struct stripe_head *sh;
1986
1987         sh = kmem_cache_zalloc(sc, gfp);
1988         if (sh) {
1989                 spin_lock_init(&sh->stripe_lock);
1990                 spin_lock_init(&sh->batch_lock);
1991                 INIT_LIST_HEAD(&sh->batch_list);
1992                 INIT_LIST_HEAD(&sh->lru);
1993                 atomic_set(&sh->count, 1);
1994         }
1995         return sh;
1996 }
1997 static int grow_one_stripe(struct r5conf *conf, gfp_t gfp)
1998 {
1999         struct stripe_head *sh;
2000
2001         sh = alloc_stripe(conf->slab_cache, gfp);
2002         if (!sh)
2003                 return 0;
2004
2005         sh->raid_conf = conf;
2006
2007         if (grow_buffers(sh, gfp)) {
2008                 shrink_buffers(sh);
2009                 kmem_cache_free(conf->slab_cache, sh);
2010                 return 0;
2011         }
2012         sh->hash_lock_index =
2013                 conf->max_nr_stripes % NR_STRIPE_HASH_LOCKS;
2014         /* we just created an active stripe so... */
2015         atomic_inc(&conf->active_stripes);
2016
2017         release_stripe(sh);
2018         conf->max_nr_stripes++;
2019         return 1;
2020 }
2021
2022 static int grow_stripes(struct r5conf *conf, int num)
2023 {
2024         struct kmem_cache *sc;
2025         int devs = max(conf->raid_disks, conf->previous_raid_disks);
2026
2027         if (conf->mddev->gendisk)
2028                 sprintf(conf->cache_name[0],
2029                         "raid%d-%s", conf->level, mdname(conf->mddev));
2030         else
2031                 sprintf(conf->cache_name[0],
2032                         "raid%d-%p", conf->level, conf->mddev);
2033         sprintf(conf->cache_name[1], "%s-alt", conf->cache_name[0]);
2034
2035         conf->active_name = 0;
2036         sc = kmem_cache_create(conf->cache_name[conf->active_name],
2037                                sizeof(struct stripe_head)+(devs-1)*sizeof(struct r5dev),
2038                                0, 0, NULL);
2039         if (!sc)
2040                 return 1;
2041         conf->slab_cache = sc;
2042         conf->pool_size = devs;
2043         while (num--)
2044                 if (!grow_one_stripe(conf, GFP_KERNEL))
2045                         return 1;
2046
2047         return 0;
2048 }
2049
2050 /**
2051  * scribble_len - return the required size of the scribble region
2052  * @num - total number of disks in the array
2053  *
2054  * The size must be enough to contain:
2055  * 1/ a struct page pointer for each device in the array +2
2056  * 2/ room to convert each entry in (1) to its corresponding dma
2057  *    (dma_map_page()) or page (page_address()) address.
2058  *
2059  * Note: the +2 is for the destination buffers of the ddf/raid6 case where we
2060  * calculate over all devices (not just the data blocks), using zeros in place
2061  * of the P and Q blocks.
2062  */
2063 static struct flex_array *scribble_alloc(int num, int cnt, gfp_t flags)
2064 {
2065         struct flex_array *ret;
2066         size_t len;
2067
2068         len = sizeof(struct page *) * (num+2) + sizeof(addr_conv_t) * (num+2);
2069         ret = flex_array_alloc(len, cnt, flags);
2070         if (!ret)
2071                 return NULL;
2072         /* always prealloc all elements, so no locking is required */
2073         if (flex_array_prealloc(ret, 0, cnt, flags)) {
2074                 flex_array_free(ret);
2075                 return NULL;
2076         }
2077         return ret;
2078 }
2079
2080 static int resize_chunks(struct r5conf *conf, int new_disks, int new_sectors)
2081 {
2082         unsigned long cpu;
2083         int err = 0;
2084
2085         mddev_suspend(conf->mddev);
2086         get_online_cpus();
2087         for_each_present_cpu(cpu) {
2088                 struct raid5_percpu *percpu;
2089                 struct flex_array *scribble;
2090
2091                 percpu = per_cpu_ptr(conf->percpu, cpu);
2092                 scribble = scribble_alloc(new_disks,
2093                                           new_sectors / STRIPE_SECTORS,
2094                                           GFP_NOIO);
2095
2096                 if (scribble) {
2097                         flex_array_free(percpu->scribble);
2098                         percpu->scribble = scribble;
2099                 } else {
2100                         err = -ENOMEM;
2101                         break;
2102                 }
2103         }
2104         put_online_cpus();
2105         mddev_resume(conf->mddev);
2106         return err;
2107 }
2108
2109 static int resize_stripes(struct r5conf *conf, int newsize)
2110 {
2111         /* Make all the stripes able to hold 'newsize' devices.
2112          * New slots in each stripe get 'page' set to a new page.
2113          *
2114          * This happens in stages:
2115          * 1/ create a new kmem_cache and allocate the required number of
2116          *    stripe_heads.
2117          * 2/ gather all the old stripe_heads and transfer the pages across
2118          *    to the new stripe_heads.  This will have the side effect of
2119          *    freezing the array as once all stripe_heads have been collected,
2120          *    no IO will be possible.  Old stripe heads are freed once their
2121          *    pages have been transferred over, and the old kmem_cache is
2122          *    freed when all stripes are done.
2123          * 3/ reallocate conf->disks to be suitable bigger.  If this fails,
2124          *    we simple return a failre status - no need to clean anything up.
2125          * 4/ allocate new pages for the new slots in the new stripe_heads.
2126          *    If this fails, we don't bother trying the shrink the
2127          *    stripe_heads down again, we just leave them as they are.
2128          *    As each stripe_head is processed the new one is released into
2129          *    active service.
2130          *
2131          * Once step2 is started, we cannot afford to wait for a write,
2132          * so we use GFP_NOIO allocations.
2133          */
2134         struct stripe_head *osh, *nsh;
2135         LIST_HEAD(newstripes);
2136         struct disk_info *ndisks;
2137         int err;
2138         struct kmem_cache *sc;
2139         int i;
2140         int hash, cnt;
2141
2142         if (newsize <= conf->pool_size)
2143                 return 0; /* never bother to shrink */
2144
2145         err = md_allow_write(conf->mddev);
2146         if (err)
2147                 return err;
2148
2149         /* Step 1 */
2150         sc = kmem_cache_create(conf->cache_name[1-conf->active_name],
2151                                sizeof(struct stripe_head)+(newsize-1)*sizeof(struct r5dev),
2152                                0, 0, NULL);
2153         if (!sc)
2154                 return -ENOMEM;
2155
2156         for (i = conf->max_nr_stripes; i; i--) {
2157                 nsh = alloc_stripe(sc, GFP_KERNEL);
2158                 if (!nsh)
2159                         break;
2160
2161                 nsh->raid_conf = conf;
2162                 list_add(&nsh->lru, &newstripes);
2163         }
2164         if (i) {
2165                 /* didn't get enough, give up */
2166                 while (!list_empty(&newstripes)) {
2167                         nsh = list_entry(newstripes.next, struct stripe_head, lru);
2168                         list_del(&nsh->lru);
2169                         kmem_cache_free(sc, nsh);
2170                 }
2171                 kmem_cache_destroy(sc);
2172                 return -ENOMEM;
2173         }
2174         /* Step 2 - Must use GFP_NOIO now.
2175          * OK, we have enough stripes, start collecting inactive
2176          * stripes and copying them over
2177          */
2178         hash = 0;
2179         cnt = 0;
2180         list_for_each_entry(nsh, &newstripes, lru) {
2181                 lock_device_hash_lock(conf, hash);
2182                 wait_event_cmd(conf->wait_for_stripe,
2183                                     !list_empty(conf->inactive_list + hash),
2184                                     unlock_device_hash_lock(conf, hash),
2185                                     lock_device_hash_lock(conf, hash));
2186                 osh = get_free_stripe(conf, hash);
2187                 unlock_device_hash_lock(conf, hash);
2188
2189                 for(i=0; i<conf->pool_size; i++) {
2190                         nsh->dev[i].page = osh->dev[i].page;
2191                         nsh->dev[i].orig_page = osh->dev[i].page;
2192                 }
2193                 nsh->hash_lock_index = hash;
2194                 kmem_cache_free(conf->slab_cache, osh);
2195                 cnt++;
2196                 if (cnt >= conf->max_nr_stripes / NR_STRIPE_HASH_LOCKS +
2197                     !!((conf->max_nr_stripes % NR_STRIPE_HASH_LOCKS) > hash)) {
2198                         hash++;
2199                         cnt = 0;
2200                 }
2201         }
2202         kmem_cache_destroy(conf->slab_cache);
2203
2204         /* Step 3.
2205          * At this point, we are holding all the stripes so the array
2206          * is completely stalled, so now is a good time to resize
2207          * conf->disks and the scribble region
2208          */
2209         ndisks = kzalloc(newsize * sizeof(struct disk_info), GFP_NOIO);
2210         if (ndisks) {
2211                 for (i=0; i<conf->raid_disks; i++)
2212                         ndisks[i] = conf->disks[i];
2213                 kfree(conf->disks);
2214                 conf->disks = ndisks;
2215         } else
2216                 err = -ENOMEM;
2217
2218         /* Step 4, return new stripes to service */
2219         while(!list_empty(&newstripes)) {
2220                 nsh = list_entry(newstripes.next, struct stripe_head, lru);
2221                 list_del_init(&nsh->lru);
2222
2223                 for (i=conf->raid_disks; i < newsize; i++)
2224                         if (nsh->dev[i].page == NULL) {
2225                                 struct page *p = alloc_page(GFP_NOIO);
2226                                 nsh->dev[i].page = p;
2227                                 nsh->dev[i].orig_page = p;
2228                                 if (!p)
2229                                         err = -ENOMEM;
2230                         }
2231                 release_stripe(nsh);
2232         }
2233         /* critical section pass, GFP_NOIO no longer needed */
2234
2235         conf->slab_cache = sc;
2236         conf->active_name = 1-conf->active_name;
2237         if (!err)
2238                 conf->pool_size = newsize;
2239         return err;
2240 }
2241
2242 static int drop_one_stripe(struct r5conf *conf)
2243 {
2244         struct stripe_head *sh;
2245         int hash = (conf->max_nr_stripes - 1) % NR_STRIPE_HASH_LOCKS;
2246
2247         spin_lock_irq(conf->hash_locks + hash);
2248         sh = get_free_stripe(conf, hash);
2249         spin_unlock_irq(conf->hash_locks + hash);
2250         if (!sh)
2251                 return 0;
2252         BUG_ON(atomic_read(&sh->count));
2253         shrink_buffers(sh);
2254         kmem_cache_free(conf->slab_cache, sh);
2255         atomic_dec(&conf->active_stripes);
2256         conf->max_nr_stripes--;
2257         return 1;
2258 }
2259
2260 static void shrink_stripes(struct r5conf *conf)
2261 {
2262         while (conf->max_nr_stripes &&
2263                drop_one_stripe(conf))
2264                 ;
2265
2266         if (conf->slab_cache)
2267                 kmem_cache_destroy(conf->slab_cache);
2268         conf->slab_cache = NULL;
2269 }
2270
2271 static void raid5_end_read_request(struct bio * bi, int error)
2272 {
2273         struct stripe_head *sh = bi->bi_private;
2274         struct r5conf *conf = sh->raid_conf;
2275         int disks = sh->disks, i;
2276         int uptodate = test_bit(BIO_UPTODATE, &bi->bi_flags);
2277         char b[BDEVNAME_SIZE];
2278         struct md_rdev *rdev = NULL;
2279         sector_t s;
2280
2281         for (i=0 ; i<disks; i++)
2282                 if (bi == &sh->dev[i].req)
2283                         break;
2284
2285         pr_debug("end_read_request %llu/%d, count: %d, uptodate %d.\n",
2286                 (unsigned long long)sh->sector, i, atomic_read(&sh->count),
2287                 uptodate);
2288         if (i == disks) {
2289                 BUG();
2290                 return;
2291         }
2292         if (test_bit(R5_ReadRepl, &sh->dev[i].flags))
2293                 /* If replacement finished while this request was outstanding,
2294                  * 'replacement' might be NULL already.
2295                  * In that case it moved down to 'rdev'.
2296                  * rdev is not removed until all requests are finished.
2297                  */
2298                 rdev = conf->disks[i].replacement;
2299         if (!rdev)
2300                 rdev = conf->disks[i].rdev;
2301
2302         if (use_new_offset(conf, sh))
2303                 s = sh->sector + rdev->new_data_offset;
2304         else
2305                 s = sh->sector + rdev->data_offset;
2306         if (uptodate) {
2307                 set_bit(R5_UPTODATE, &sh->dev[i].flags);
2308                 if (test_bit(R5_ReadError, &sh->dev[i].flags)) {
2309                         /* Note that this cannot happen on a
2310                          * replacement device.  We just fail those on
2311                          * any error
2312                          */
2313                         printk_ratelimited(
2314                                 KERN_INFO
2315                                 "md/raid:%s: read error corrected"
2316                                 " (%lu sectors at %llu on %s)\n",
2317                                 mdname(conf->mddev), STRIPE_SECTORS,
2318                                 (unsigned long long)s,
2319                                 bdevname(rdev->bdev, b));
2320                         atomic_add(STRIPE_SECTORS, &rdev->corrected_errors);
2321                         clear_bit(R5_ReadError, &sh->dev[i].flags);
2322                         clear_bit(R5_ReWrite, &sh->dev[i].flags);
2323                 } else if (test_bit(R5_ReadNoMerge, &sh->dev[i].flags))
2324                         clear_bit(R5_ReadNoMerge, &sh->dev[i].flags);
2325
2326                 if (atomic_read(&rdev->read_errors))
2327                         atomic_set(&rdev->read_errors, 0);
2328         } else {
2329                 const char *bdn = bdevname(rdev->bdev, b);
2330                 int retry = 0;
2331                 int set_bad = 0;
2332
2333                 clear_bit(R5_UPTODATE, &sh->dev[i].flags);
2334                 atomic_inc(&rdev->read_errors);
2335                 if (test_bit(R5_ReadRepl, &sh->dev[i].flags))
2336                         printk_ratelimited(
2337                                 KERN_WARNING
2338                                 "md/raid:%s: read error on replacement device "
2339                                 "(sector %llu on %s).\n",
2340                                 mdname(conf->mddev),
2341                                 (unsigned long long)s,
2342                                 bdn);
2343                 else if (conf->mddev->degraded >= conf->max_degraded) {
2344                         set_bad = 1;
2345                         printk_ratelimited(
2346                                 KERN_WARNING
2347                                 "md/raid:%s: read error not correctable "
2348                                 "(sector %llu on %s).\n",
2349                                 mdname(conf->mddev),
2350                                 (unsigned long long)s,
2351                                 bdn);
2352                 } else if (test_bit(R5_ReWrite, &sh->dev[i].flags)) {
2353                         /* Oh, no!!! */
2354                         set_bad = 1;
2355                         printk_ratelimited(
2356                                 KERN_WARNING
2357                                 "md/raid:%s: read error NOT corrected!! "
2358                                 "(sector %llu on %s).\n",
2359                                 mdname(conf->mddev),
2360                                 (unsigned long long)s,
2361                                 bdn);
2362                 } else if (atomic_read(&rdev->read_errors)
2363                          > conf->max_nr_stripes)
2364                         printk(KERN_WARNING
2365                                "md/raid:%s: Too many read errors, failing device %s.\n",
2366                                mdname(conf->mddev), bdn);
2367                 else
2368                         retry = 1;
2369                 if (set_bad && test_bit(In_sync, &rdev->flags)
2370                     && !test_bit(R5_ReadNoMerge, &sh->dev[i].flags))
2371                         retry = 1;
2372                 if (retry)
2373                         if (test_bit(R5_ReadNoMerge, &sh->dev[i].flags)) {
2374                                 set_bit(R5_ReadError, &sh->dev[i].flags);
2375                                 clear_bit(R5_ReadNoMerge, &sh->dev[i].flags);
2376                         } else
2377                                 set_bit(R5_ReadNoMerge, &sh->dev[i].flags);
2378                 else {
2379                         clear_bit(R5_ReadError, &sh->dev[i].flags);
2380                         clear_bit(R5_ReWrite, &sh->dev[i].flags);
2381                         if (!(set_bad
2382                               && test_bit(In_sync, &rdev->flags)
2383                               && rdev_set_badblocks(
2384                                       rdev, sh->sector, STRIPE_SECTORS, 0)))
2385                                 md_error(conf->mddev, rdev);
2386                 }
2387         }
2388         rdev_dec_pending(rdev, conf->mddev);
2389         clear_bit(R5_LOCKED, &sh->dev[i].flags);
2390         set_bit(STRIPE_HANDLE, &sh->state);
2391         release_stripe(sh);
2392 }
2393
2394 static void raid5_end_write_request(struct bio *bi, int error)
2395 {
2396         struct stripe_head *sh = bi->bi_private;
2397         struct r5conf *conf = sh->raid_conf;
2398         int disks = sh->disks, i;
2399         struct md_rdev *uninitialized_var(rdev);
2400         int uptodate = test_bit(BIO_UPTODATE, &bi->bi_flags);
2401         sector_t first_bad;
2402         int bad_sectors;
2403         int replacement = 0;
2404
2405         for (i = 0 ; i < disks; i++) {
2406                 if (bi == &sh->dev[i].req) {
2407                         rdev = conf->disks[i].rdev;
2408                         break;
2409                 }
2410                 if (bi == &sh->dev[i].rreq) {
2411                         rdev = conf->disks[i].replacement;
2412                         if (rdev)
2413                                 replacement = 1;
2414                         else
2415                                 /* rdev was removed and 'replacement'
2416                                  * replaced it.  rdev is not removed
2417                                  * until all requests are finished.
2418                                  */
2419                                 rdev = conf->disks[i].rdev;
2420                         break;
2421                 }
2422         }
2423         pr_debug("end_write_request %llu/%d, count %d, uptodate: %d.\n",
2424                 (unsigned long long)sh->sector, i, atomic_read(&sh->count),
2425                 uptodate);
2426         if (i == disks) {
2427                 BUG();
2428                 return;
2429         }
2430
2431         if (replacement) {
2432                 if (!uptodate)
2433                         md_error(conf->mddev, rdev);
2434                 else if (is_badblock(rdev, sh->sector,
2435                                      STRIPE_SECTORS,
2436                                      &first_bad, &bad_sectors))
2437                         set_bit(R5_MadeGoodRepl, &sh->dev[i].flags);
2438         } else {
2439                 if (!uptodate) {
2440                         set_bit(STRIPE_DEGRADED, &sh->state);
2441                         set_bit(WriteErrorSeen, &rdev->flags);
2442                         set_bit(R5_WriteError, &sh->dev[i].flags);
2443                         if (!test_and_set_bit(WantReplacement, &rdev->flags))
2444                                 set_bit(MD_RECOVERY_NEEDED,
2445                                         &rdev->mddev->recovery);
2446                 } else if (is_badblock(rdev, sh->sector,
2447                                        STRIPE_SECTORS,
2448                                        &first_bad, &bad_sectors)) {
2449                         set_bit(R5_MadeGood, &sh->dev[i].flags);
2450                         if (test_bit(R5_ReadError, &sh->dev[i].flags))
2451                                 /* That was a successful write so make
2452                                  * sure it looks like we already did
2453                                  * a re-write.
2454                                  */
2455                                 set_bit(R5_ReWrite, &sh->dev[i].flags);
2456                 }
2457         }
2458         rdev_dec_pending(rdev, conf->mddev);
2459
2460         if (sh->batch_head && !uptodate && !replacement)
2461                 set_bit(STRIPE_BATCH_ERR, &sh->batch_head->state);
2462
2463         if (!test_and_clear_bit(R5_DOUBLE_LOCKED, &sh->dev[i].flags))
2464                 clear_bit(R5_LOCKED, &sh->dev[i].flags);
2465         set_bit(STRIPE_HANDLE, &sh->state);
2466         release_stripe(sh);
2467
2468         if (sh->batch_head && sh != sh->batch_head)
2469                 release_stripe(sh->batch_head);
2470 }
2471
2472 static sector_t compute_blocknr(struct stripe_head *sh, int i, int previous);
2473
2474 static void raid5_build_block(struct stripe_head *sh, int i, int previous)
2475 {
2476         struct r5dev *dev = &sh->dev[i];
2477
2478         bio_init(&dev->req);
2479         dev->req.bi_io_vec = &dev->vec;
2480         dev->req.bi_max_vecs = 1;
2481         dev->req.bi_private = sh;
2482
2483         bio_init(&dev->rreq);
2484         dev->rreq.bi_io_vec = &dev->rvec;
2485         dev->rreq.bi_max_vecs = 1;
2486         dev->rreq.bi_private = sh;
2487
2488         dev->flags = 0;
2489         dev->sector = compute_blocknr(sh, i, previous);
2490 }
2491
2492 static void error(struct mddev *mddev, struct md_rdev *rdev)
2493 {
2494         char b[BDEVNAME_SIZE];
2495         struct r5conf *conf = mddev->private;
2496         unsigned long flags;
2497         pr_debug("raid456: error called\n");
2498
2499         spin_lock_irqsave(&conf->device_lock, flags);
2500         clear_bit(In_sync, &rdev->flags);
2501         mddev->degraded = calc_degraded(conf);
2502         spin_unlock_irqrestore(&conf->device_lock, flags);
2503         set_bit(MD_RECOVERY_INTR, &mddev->recovery);
2504
2505         set_bit(Blocked, &rdev->flags);
2506         set_bit(Faulty, &rdev->flags);
2507         set_bit(MD_CHANGE_DEVS, &mddev->flags);
2508         printk(KERN_ALERT
2509                "md/raid:%s: Disk failure on %s, disabling device.\n"
2510                "md/raid:%s: Operation continuing on %d devices.\n",
2511                mdname(mddev),
2512                bdevname(rdev->bdev, b),
2513                mdname(mddev),
2514                conf->raid_disks - mddev->degraded);
2515 }
2516
2517 /*
2518  * Input: a 'big' sector number,
2519  * Output: index of the data and parity disk, and the sector # in them.
2520  */
2521 static sector_t raid5_compute_sector(struct r5conf *conf, sector_t r_sector,
2522                                      int previous, int *dd_idx,
2523                                      struct stripe_head *sh)
2524 {
2525         sector_t stripe, stripe2;
2526         sector_t chunk_number;
2527         unsigned int chunk_offset;
2528         int pd_idx, qd_idx;
2529         int ddf_layout = 0;
2530         sector_t new_sector;
2531         int algorithm = previous ? conf->prev_algo
2532                                  : conf->algorithm;
2533         int sectors_per_chunk = previous ? conf->prev_chunk_sectors
2534                                          : conf->chunk_sectors;
2535         int raid_disks = previous ? conf->previous_raid_disks
2536                                   : conf->raid_disks;
2537         int data_disks = raid_disks - conf->max_degraded;
2538
2539         /* First compute the information on this sector */
2540
2541         /*
2542          * Compute the chunk number and the sector offset inside the chunk
2543          */
2544         chunk_offset = sector_div(r_sector, sectors_per_chunk);
2545         chunk_number = r_sector;
2546
2547         /*
2548          * Compute the stripe number
2549          */
2550         stripe = chunk_number;
2551         *dd_idx = sector_div(stripe, data_disks);
2552         stripe2 = stripe;
2553         /*
2554          * Select the parity disk based on the user selected algorithm.
2555          */
2556         pd_idx = qd_idx = -1;
2557         switch(conf->level) {
2558         case 4:
2559                 pd_idx = data_disks;
2560                 break;
2561         case 5:
2562                 switch (algorithm) {
2563                 case ALGORITHM_LEFT_ASYMMETRIC:
2564                         pd_idx = data_disks - sector_div(stripe2, raid_disks);
2565                         if (*dd_idx >= pd_idx)
2566                                 (*dd_idx)++;
2567                         break;
2568                 case ALGORITHM_RIGHT_ASYMMETRIC:
2569                         pd_idx = sector_div(stripe2, raid_disks);
2570                         if (*dd_idx >= pd_idx)
2571                                 (*dd_idx)++;
2572                         break;
2573                 case ALGORITHM_LEFT_SYMMETRIC:
2574                         pd_idx = data_disks - sector_div(stripe2, raid_disks);
2575                         *dd_idx = (pd_idx + 1 + *dd_idx) % raid_disks;
2576                         break;
2577                 case ALGORITHM_RIGHT_SYMMETRIC:
2578                         pd_idx = sector_div(stripe2, raid_disks);
2579                         *dd_idx = (pd_idx + 1 + *dd_idx) % raid_disks;
2580                         break;
2581                 case ALGORITHM_PARITY_0:
2582                         pd_idx = 0;
2583                         (*dd_idx)++;
2584                         break;
2585                 case ALGORITHM_PARITY_N:
2586                         pd_idx = data_disks;
2587                         break;
2588                 default:
2589                         BUG();
2590                 }
2591                 break;
2592         case 6:
2593
2594                 switch (algorithm) {
2595                 case ALGORITHM_LEFT_ASYMMETRIC:
2596                         pd_idx = raid_disks - 1 - sector_div(stripe2, raid_disks);
2597                         qd_idx = pd_idx + 1;
2598                         if (pd_idx == raid_disks-1) {
2599                                 (*dd_idx)++;    /* Q D D D P */
2600                                 qd_idx = 0;
2601                         } else if (*dd_idx >= pd_idx)
2602                                 (*dd_idx) += 2; /* D D P Q D */
2603                         break;
2604                 case ALGORITHM_RIGHT_ASYMMETRIC:
2605                         pd_idx = sector_div(stripe2, raid_disks);
2606                         qd_idx = pd_idx + 1;
2607                         if (pd_idx == raid_disks-1) {
2608                                 (*dd_idx)++;    /* Q D D D P */
2609                                 qd_idx = 0;
2610                         } else if (*dd_idx >= pd_idx)
2611                                 (*dd_idx) += 2; /* D D P Q D */
2612                         break;
2613                 case ALGORITHM_LEFT_SYMMETRIC:
2614                         pd_idx = raid_disks - 1 - sector_div(stripe2, raid_disks);
2615                         qd_idx = (pd_idx + 1) % raid_disks;
2616                         *dd_idx = (pd_idx + 2 + *dd_idx) % raid_disks;
2617                         break;
2618                 case ALGORITHM_RIGHT_SYMMETRIC:
2619                         pd_idx = sector_div(stripe2, raid_disks);
2620                         qd_idx = (pd_idx + 1) % raid_disks;
2621                         *dd_idx = (pd_idx + 2 + *dd_idx) % raid_disks;
2622                         break;
2623
2624                 case ALGORITHM_PARITY_0:
2625                         pd_idx = 0;
2626                         qd_idx = 1;
2627                         (*dd_idx) += 2;
2628                         break;
2629                 case ALGORITHM_PARITY_N:
2630                         pd_idx = data_disks;
2631                         qd_idx = data_disks + 1;
2632                         break;
2633
2634                 case ALGORITHM_ROTATING_ZERO_RESTART:
2635                         /* Exactly the same as RIGHT_ASYMMETRIC, but or
2636                          * of blocks for computing Q is different.
2637                          */
2638                         pd_idx = sector_div(stripe2, raid_disks);
2639                         qd_idx = pd_idx + 1;
2640                         if (pd_idx == raid_disks-1) {
2641                                 (*dd_idx)++;    /* Q D D D P */
2642                                 qd_idx = 0;
2643                         } else if (*dd_idx >= pd_idx)
2644                                 (*dd_idx) += 2; /* D D P Q D */
2645                         ddf_layout = 1;
2646                         break;
2647
2648                 case ALGORITHM_ROTATING_N_RESTART:
2649                         /* Same a left_asymmetric, by first stripe is
2650                          * D D D P Q  rather than
2651                          * Q D D D P
2652                          */
2653                         stripe2 += 1;
2654                         pd_idx = raid_disks - 1 - sector_div(stripe2, raid_disks);
2655                         qd_idx = pd_idx + 1;
2656                         if (pd_idx == raid_disks-1) {
2657                                 (*dd_idx)++;    /* Q D D D P */
2658                                 qd_idx = 0;
2659                         } else if (*dd_idx >= pd_idx)
2660                                 (*dd_idx) += 2; /* D D P Q D */
2661                         ddf_layout = 1;
2662                         break;
2663
2664                 case ALGORITHM_ROTATING_N_CONTINUE:
2665                         /* Same as left_symmetric but Q is before P */
2666                         pd_idx = raid_disks - 1 - sector_div(stripe2, raid_disks);
2667                         qd_idx = (pd_idx + raid_disks - 1) % raid_disks;
2668                         *dd_idx = (pd_idx + 1 + *dd_idx) % raid_disks;
2669                         ddf_layout = 1;
2670                         break;
2671
2672                 case ALGORITHM_LEFT_ASYMMETRIC_6:
2673                         /* RAID5 left_asymmetric, with Q on last device */
2674                         pd_idx = data_disks - sector_div(stripe2, raid_disks-1);
2675                         if (*dd_idx >= pd_idx)
2676                                 (*dd_idx)++;
2677                         qd_idx = raid_disks - 1;
2678                         break;
2679
2680                 case ALGORITHM_RIGHT_ASYMMETRIC_6:
2681                         pd_idx = sector_div(stripe2, raid_disks-1);
2682                         if (*dd_idx >= pd_idx)
2683                                 (*dd_idx)++;
2684                         qd_idx = raid_disks - 1;
2685                         break;
2686
2687                 case ALGORITHM_LEFT_SYMMETRIC_6:
2688                         pd_idx = data_disks - sector_div(stripe2, raid_disks-1);
2689                         *dd_idx = (pd_idx + 1 + *dd_idx) % (raid_disks-1);
2690                         qd_idx = raid_disks - 1;
2691                         break;
2692
2693                 case ALGORITHM_RIGHT_SYMMETRIC_6:
2694                         pd_idx = sector_div(stripe2, raid_disks-1);
2695                         *dd_idx = (pd_idx + 1 + *dd_idx) % (raid_disks-1);
2696                         qd_idx = raid_disks - 1;
2697                         break;
2698
2699                 case ALGORITHM_PARITY_0_6:
2700                         pd_idx = 0;
2701                         (*dd_idx)++;
2702                         qd_idx = raid_disks - 1;
2703                         break;
2704
2705                 default:
2706                         BUG();
2707                 }
2708                 break;
2709         }
2710
2711         if (sh) {
2712                 sh->pd_idx = pd_idx;
2713                 sh->qd_idx = qd_idx;
2714                 sh->ddf_layout = ddf_layout;
2715         }
2716         /*
2717          * Finally, compute the new sector number
2718          */
2719         new_sector = (sector_t)stripe * sectors_per_chunk + chunk_offset;
2720         return new_sector;
2721 }
2722
2723 static sector_t compute_blocknr(struct stripe_head *sh, int i, int previous)
2724 {
2725         struct r5conf *conf = sh->raid_conf;
2726         int raid_disks = sh->disks;
2727         int data_disks = raid_disks - conf->max_degraded;
2728         sector_t new_sector = sh->sector, check;
2729         int sectors_per_chunk = previous ? conf->prev_chunk_sectors
2730                                          : conf->chunk_sectors;
2731         int algorithm = previous ? conf->prev_algo
2732                                  : conf->algorithm;
2733         sector_t stripe;
2734         int chunk_offset;
2735         sector_t chunk_number;
2736         int dummy1, dd_idx = i;
2737         sector_t r_sector;
2738         struct stripe_head sh2;
2739
2740         chunk_offset = sector_div(new_sector, sectors_per_chunk);
2741         stripe = new_sector;
2742
2743         if (i == sh->pd_idx)
2744                 return 0;
2745         switch(conf->level) {
2746         case 4: break;
2747         case 5:
2748                 switch (algorithm) {
2749                 case ALGORITHM_LEFT_ASYMMETRIC:
2750                 case ALGORITHM_RIGHT_ASYMMETRIC:
2751                         if (i > sh->pd_idx)
2752                                 i--;
2753                         break;
2754                 case ALGORITHM_LEFT_SYMMETRIC:
2755                 case ALGORITHM_RIGHT_SYMMETRIC:
2756                         if (i < sh->pd_idx)
2757                                 i += raid_disks;
2758                         i -= (sh->pd_idx + 1);
2759                         break;
2760                 case ALGORITHM_PARITY_0:
2761                         i -= 1;
2762                         break;
2763                 case ALGORITHM_PARITY_N:
2764                         break;
2765                 default:
2766                         BUG();
2767                 }
2768                 break;
2769         case 6:
2770                 if (i == sh->qd_idx)
2771                         return 0; /* It is the Q disk */
2772                 switch (algorithm) {
2773                 case ALGORITHM_LEFT_ASYMMETRIC:
2774                 case ALGORITHM_RIGHT_ASYMMETRIC:
2775                 case ALGORITHM_ROTATING_ZERO_RESTART:
2776                 case ALGORITHM_ROTATING_N_RESTART:
2777                         if (sh->pd_idx == raid_disks-1)
2778                                 i--;    /* Q D D D P */
2779                         else if (i > sh->pd_idx)
2780                                 i -= 2; /* D D P Q D */
2781                         break;
2782                 case ALGORITHM_LEFT_SYMMETRIC:
2783                 case ALGORITHM_RIGHT_SYMMETRIC:
2784                         if (sh->pd_idx == raid_disks-1)
2785                                 i--; /* Q D D D P */
2786                         else {
2787                                 /* D D P Q D */
2788                                 if (i < sh->pd_idx)
2789                                         i += raid_disks;
2790                                 i -= (sh->pd_idx + 2);
2791                         }
2792                         break;
2793                 case ALGORITHM_PARITY_0:
2794                         i -= 2;
2795                         break;
2796                 case ALGORITHM_PARITY_N:
2797                         break;
2798                 case ALGORITHM_ROTATING_N_CONTINUE:
2799                         /* Like left_symmetric, but P is before Q */
2800                         if (sh->pd_idx == 0)
2801                                 i--;    /* P D D D Q */
2802                         else {
2803                                 /* D D Q P D */
2804                                 if (i < sh->pd_idx)
2805                                         i += raid_disks;
2806                                 i -= (sh->pd_idx + 1);
2807                         }
2808                         break;
2809                 case ALGORITHM_LEFT_ASYMMETRIC_6:
2810                 case ALGORITHM_RIGHT_ASYMMETRIC_6:
2811                         if (i > sh->pd_idx)
2812                                 i--;
2813                         break;
2814                 case ALGORITHM_LEFT_SYMMETRIC_6:
2815                 case ALGORITHM_RIGHT_SYMMETRIC_6:
2816                         if (i < sh->pd_idx)
2817                                 i += data_disks + 1;
2818                         i -= (sh->pd_idx + 1);
2819                         break;
2820                 case ALGORITHM_PARITY_0_6:
2821                         i -= 1;
2822                         break;
2823                 default:
2824                         BUG();
2825                 }
2826                 break;
2827         }
2828
2829         chunk_number = stripe * data_disks + i;
2830         r_sector = chunk_number * sectors_per_chunk + chunk_offset;
2831
2832         check = raid5_compute_sector(conf, r_sector,
2833                                      previous, &dummy1, &sh2);
2834         if (check != sh->sector || dummy1 != dd_idx || sh2.pd_idx != sh->pd_idx
2835                 || sh2.qd_idx != sh->qd_idx) {
2836                 printk(KERN_ERR "md/raid:%s: compute_blocknr: map not correct\n",
2837                        mdname(conf->mddev));
2838                 return 0;
2839         }
2840         return r_sector;
2841 }
2842
2843 static void
2844 schedule_reconstruction(struct stripe_head *sh, struct stripe_head_state *s,
2845                          int rcw, int expand)
2846 {
2847         int i, pd_idx = sh->pd_idx, qd_idx = sh->qd_idx, disks = sh->disks;
2848         struct r5conf *conf = sh->raid_conf;
2849         int level = conf->level;
2850
2851         if (rcw) {
2852
2853                 for (i = disks; i--; ) {
2854                         struct r5dev *dev = &sh->dev[i];
2855
2856                         if (dev->towrite) {
2857                                 set_bit(R5_LOCKED, &dev->flags);
2858                                 set_bit(R5_Wantdrain, &dev->flags);
2859                                 if (!expand)
2860                                         clear_bit(R5_UPTODATE, &dev->flags);
2861                                 s->locked++;
2862                         }
2863                 }
2864                 /* if we are not expanding this is a proper write request, and
2865                  * there will be bios with new data to be drained into the
2866                  * stripe cache
2867                  */
2868                 if (!expand) {
2869                         if (!s->locked)
2870                                 /* False alarm, nothing to do */
2871                                 return;
2872                         sh->reconstruct_state = reconstruct_state_drain_run;
2873                         set_bit(STRIPE_OP_BIODRAIN, &s->ops_request);
2874                 } else
2875                         sh->reconstruct_state = reconstruct_state_run;
2876
2877                 set_bit(STRIPE_OP_RECONSTRUCT, &s->ops_request);
2878
2879                 if (s->locked + conf->max_degraded == disks)
2880                         if (!test_and_set_bit(STRIPE_FULL_WRITE, &sh->state))
2881                                 atomic_inc(&conf->pending_full_writes);
2882         } else {
2883                 BUG_ON(!(test_bit(R5_UPTODATE, &sh->dev[pd_idx].flags) ||
2884                         test_bit(R5_Wantcompute, &sh->dev[pd_idx].flags)));
2885                 BUG_ON(level == 6 &&
2886                         (!(test_bit(R5_UPTODATE, &sh->dev[qd_idx].flags) ||
2887                            test_bit(R5_Wantcompute, &sh->dev[qd_idx].flags))));
2888
2889                 for (i = disks; i--; ) {
2890                         struct r5dev *dev = &sh->dev[i];
2891                         if (i == pd_idx || i == qd_idx)
2892                                 continue;
2893
2894                         if (dev->towrite &&
2895                             (test_bit(R5_UPTODATE, &dev->flags) ||
2896                              test_bit(R5_Wantcompute, &dev->flags))) {
2897                                 set_bit(R5_Wantdrain, &dev->flags);
2898                                 set_bit(R5_LOCKED, &dev->flags);
2899                                 clear_bit(R5_UPTODATE, &dev->flags);
2900                                 s->locked++;
2901                         }
2902                 }
2903                 if (!s->locked)
2904                         /* False alarm - nothing to do */
2905                         return;
2906                 sh->reconstruct_state = reconstruct_state_prexor_drain_run;
2907                 set_bit(STRIPE_OP_PREXOR, &s->ops_request);
2908                 set_bit(STRIPE_OP_BIODRAIN, &s->ops_request);
2909                 set_bit(STRIPE_OP_RECONSTRUCT, &s->ops_request);
2910         }
2911
2912         /* keep the parity disk(s) locked while asynchronous operations
2913          * are in flight
2914          */
2915         set_bit(R5_LOCKED, &sh->dev[pd_idx].flags);
2916         clear_bit(R5_UPTODATE, &sh->dev[pd_idx].flags);
2917         s->locked++;
2918
2919         if (level == 6) {
2920                 int qd_idx = sh->qd_idx;
2921                 struct r5dev *dev = &sh->dev[qd_idx];
2922
2923                 set_bit(R5_LOCKED, &dev->flags);
2924                 clear_bit(R5_UPTODATE, &dev->flags);
2925                 s->locked++;
2926         }
2927
2928         pr_debug("%s: stripe %llu locked: %d ops_request: %lx\n",
2929                 __func__, (unsigned long long)sh->sector,
2930                 s->locked, s->ops_request);
2931 }
2932
2933 /*
2934  * Each stripe/dev can have one or more bion attached.
2935  * toread/towrite point to the first in a chain.
2936  * The bi_next chain must be in order.
2937  */
2938 static int add_stripe_bio(struct stripe_head *sh, struct bio *bi, int dd_idx,
2939                           int forwrite, int previous)
2940 {
2941         struct bio **bip;
2942         struct r5conf *conf = sh->raid_conf;
2943         int firstwrite=0;
2944
2945         pr_debug("adding bi b#%llu to stripe s#%llu\n",
2946                 (unsigned long long)bi->bi_iter.bi_sector,
2947                 (unsigned long long)sh->sector);
2948
2949         /*
2950          * If several bio share a stripe. The bio bi_phys_segments acts as a
2951          * reference count to avoid race. The reference count should already be
2952          * increased before this function is called (for example, in
2953          * make_request()), so other bio sharing this stripe will not free the
2954          * stripe. If a stripe is owned by one stripe, the stripe lock will
2955          * protect it.
2956          */
2957         spin_lock_irq(&sh->stripe_lock);
2958         /* Don't allow new IO added to stripes in batch list */
2959         if (sh->batch_head)
2960                 goto overlap;
2961         if (forwrite) {
2962                 bip = &sh->dev[dd_idx].towrite;
2963                 if (*bip == NULL)
2964                         firstwrite = 1;
2965         } else
2966                 bip = &sh->dev[dd_idx].toread;
2967         while (*bip && (*bip)->bi_iter.bi_sector < bi->bi_iter.bi_sector) {
2968                 if (bio_end_sector(*bip) > bi->bi_iter.bi_sector)
2969                         goto overlap;
2970                 bip = & (*bip)->bi_next;
2971         }
2972         if (*bip && (*bip)->bi_iter.bi_sector < bio_end_sector(bi))
2973                 goto overlap;
2974
2975         if (!forwrite || previous)
2976                 clear_bit(STRIPE_BATCH_READY, &sh->state);
2977
2978         BUG_ON(*bip && bi->bi_next && (*bip) != bi->bi_next);
2979         if (*bip)
2980                 bi->bi_next = *bip;
2981         *bip = bi;
2982         raid5_inc_bi_active_stripes(bi);
2983
2984         if (forwrite) {
2985                 /* check if page is covered */
2986                 sector_t sector = sh->dev[dd_idx].sector;
2987                 for (bi=sh->dev[dd_idx].towrite;
2988                      sector < sh->dev[dd_idx].sector + STRIPE_SECTORS &&
2989                              bi && bi->bi_iter.bi_sector <= sector;
2990                      bi = r5_next_bio(bi, sh->dev[dd_idx].sector)) {
2991                         if (bio_end_sector(bi) >= sector)
2992                                 sector = bio_end_sector(bi);
2993                 }
2994                 if (sector >= sh->dev[dd_idx].sector + STRIPE_SECTORS)
2995                         if (!test_and_set_bit(R5_OVERWRITE, &sh->dev[dd_idx].flags))
2996                                 sh->overwrite_disks++;
2997         }
2998
2999         pr_debug("added bi b#%llu to stripe s#%llu, disk %d.\n",
3000                 (unsigned long long)(*bip)->bi_iter.bi_sector,
3001                 (unsigned long long)sh->sector, dd_idx);
3002
3003         if (conf->mddev->bitmap && firstwrite) {
3004                 /* Cannot hold spinlock over bitmap_startwrite,
3005                  * but must ensure this isn't added to a batch until
3006                  * we have added to the bitmap and set bm_seq.
3007                  * So set STRIPE_BITMAP_PENDING to prevent
3008                  * batching.
3009                  * If multiple add_stripe_bio() calls race here they
3010                  * much all set STRIPE_BITMAP_PENDING.  So only the first one
3011                  * to complete "bitmap_startwrite" gets to set
3012                  * STRIPE_BIT_DELAY.  This is important as once a stripe
3013                  * is added to a batch, STRIPE_BIT_DELAY cannot be changed
3014                  * any more.
3015                  */
3016                 set_bit(STRIPE_BITMAP_PENDING, &sh->state);
3017                 spin_unlock_irq(&sh->stripe_lock);
3018                 bitmap_startwrite(conf->mddev->bitmap, sh->sector,
3019                                   STRIPE_SECTORS, 0);
3020                 spin_lock_irq(&sh->stripe_lock);
3021                 clear_bit(STRIPE_BITMAP_PENDING, &sh->state);
3022                 if (!sh->batch_head) {
3023                         sh->bm_seq = conf->seq_flush+1;
3024                         set_bit(STRIPE_BIT_DELAY, &sh->state);
3025                 }
3026         }
3027         spin_unlock_irq(&sh->stripe_lock);
3028
3029         if (stripe_can_batch(sh))
3030                 stripe_add_to_batch_list(conf, sh);
3031         return 1;
3032
3033  overlap:
3034         set_bit(R5_Overlap, &sh->dev[dd_idx].flags);
3035         spin_unlock_irq(&sh->stripe_lock);
3036         return 0;
3037 }
3038
3039 static void end_reshape(struct r5conf *conf);
3040
3041 static void stripe_set_idx(sector_t stripe, struct r5conf *conf, int previous,
3042                             struct stripe_head *sh)
3043 {
3044         int sectors_per_chunk =
3045                 previous ? conf->prev_chunk_sectors : conf->chunk_sectors;
3046         int dd_idx;
3047         int chunk_offset = sector_div(stripe, sectors_per_chunk);
3048         int disks = previous ? conf->previous_raid_disks : conf->raid_disks;
3049
3050         raid5_compute_sector(conf,
3051                              stripe * (disks - conf->max_degraded)
3052                              *sectors_per_chunk + chunk_offset,
3053                              previous,
3054                              &dd_idx, sh);
3055 }
3056
3057 static void
3058 handle_failed_stripe(struct r5conf *conf, struct stripe_head *sh,
3059                                 struct stripe_head_state *s, int disks,
3060                                 struct bio **return_bi)
3061 {
3062         int i;
3063         BUG_ON(sh->batch_head);
3064         for (i = disks; i--; ) {
3065                 struct bio *bi;
3066                 int bitmap_end = 0;
3067
3068                 if (test_bit(R5_ReadError, &sh->dev[i].flags)) {
3069                         struct md_rdev *rdev;
3070                         rcu_read_lock();
3071                         rdev = rcu_dereference(conf->disks[i].rdev);
3072                         if (rdev && test_bit(In_sync, &rdev->flags))
3073                                 atomic_inc(&rdev->nr_pending);
3074                         else
3075                                 rdev = NULL;
3076                         rcu_read_unlock();
3077                         if (rdev) {
3078                                 if (!rdev_set_badblocks(
3079                                             rdev,
3080                                             sh->sector,
3081                                             STRIPE_SECTORS, 0))
3082                                         md_error(conf->mddev, rdev);
3083                                 rdev_dec_pending(rdev, conf->mddev);
3084                         }
3085                 }
3086                 spin_lock_irq(&sh->stripe_lock);
3087                 /* fail all writes first */
3088                 bi = sh->dev[i].towrite;
3089                 sh->dev[i].towrite = NULL;
3090                 sh->overwrite_disks = 0;
3091                 spin_unlock_irq(&sh->stripe_lock);
3092                 if (bi)
3093                         bitmap_end = 1;
3094
3095                 if (test_and_clear_bit(R5_Overlap, &sh->dev[i].flags))
3096                         wake_up(&conf->wait_for_overlap);
3097
3098                 while (bi && bi->bi_iter.bi_sector <
3099                         sh->dev[i].sector + STRIPE_SECTORS) {
3100                         struct bio *nextbi = r5_next_bio(bi, sh->dev[i].sector);
3101                         clear_bit(BIO_UPTODATE, &bi->bi_flags);
3102                         if (!raid5_dec_bi_active_stripes(bi)) {
3103                                 md_write_end(conf->mddev);
3104                                 bi->bi_next = *return_bi;
3105                                 *return_bi = bi;
3106                         }
3107                         bi = nextbi;
3108                 }
3109                 if (bitmap_end)
3110                         bitmap_endwrite(conf->mddev->bitmap, sh->sector,
3111                                 STRIPE_SECTORS, 0, 0);
3112                 bitmap_end = 0;
3113                 /* and fail all 'written' */
3114                 bi = sh->dev[i].written;
3115                 sh->dev[i].written = NULL;
3116                 if (test_and_clear_bit(R5_SkipCopy, &sh->dev[i].flags)) {
3117                         WARN_ON(test_bit(R5_UPTODATE, &sh->dev[i].flags));
3118                         sh->dev[i].page = sh->dev[i].orig_page;
3119                 }
3120
3121                 if (bi) bitmap_end = 1;
3122                 while (bi && bi->bi_iter.bi_sector <
3123                        sh->dev[i].sector + STRIPE_SECTORS) {
3124                         struct bio *bi2 = r5_next_bio(bi, sh->dev[i].sector);
3125                         clear_bit(BIO_UPTODATE, &bi->bi_flags);
3126                         if (!raid5_dec_bi_active_stripes(bi)) {
3127                                 md_write_end(conf->mddev);
3128                                 bi->bi_next = *return_bi;
3129                                 *return_bi = bi;
3130                         }
3131                         bi = bi2;
3132                 }
3133
3134                 /* fail any reads if this device is non-operational and
3135                  * the data has not reached the cache yet.
3136                  */
3137                 if (!test_bit(R5_Wantfill, &sh->dev[i].flags) &&
3138                     (!test_bit(R5_Insync, &sh->dev[i].flags) ||
3139                       test_bit(R5_ReadError, &sh->dev[i].flags))) {
3140                         spin_lock_irq(&sh->stripe_lock);
3141                         bi = sh->dev[i].toread;
3142                         sh->dev[i].toread = NULL;
3143                         spin_unlock_irq(&sh->stripe_lock);
3144                         if (test_and_clear_bit(R5_Overlap, &sh->dev[i].flags))
3145                                 wake_up(&conf->wait_for_overlap);
3146                         while (bi && bi->bi_iter.bi_sector <
3147                                sh->dev[i].sector + STRIPE_SECTORS) {
3148                                 struct bio *nextbi =
3149                                         r5_next_bio(bi, sh->dev[i].sector);
3150                                 clear_bit(BIO_UPTODATE, &bi->bi_flags);
3151                                 if (!raid5_dec_bi_active_stripes(bi)) {
3152                                         bi->bi_next = *return_bi;
3153                                         *return_bi = bi;
3154                                 }
3155                                 bi = nextbi;
3156                         }
3157                 }
3158                 if (bitmap_end)
3159                         bitmap_endwrite(conf->mddev->bitmap, sh->sector,
3160                                         STRIPE_SECTORS, 0, 0);
3161                 /* If we were in the middle of a write the parity block might
3162                  * still be locked - so just clear all R5_LOCKED flags
3163                  */
3164                 clear_bit(R5_LOCKED, &sh->dev[i].flags);
3165         }
3166
3167         if (test_and_clear_bit(STRIPE_FULL_WRITE, &sh->state))
3168                 if (atomic_dec_and_test(&conf->pending_full_writes))
3169                         md_wakeup_thread(conf->mddev->thread);
3170 }
3171
3172 static void
3173 handle_failed_sync(struct r5conf *conf, struct stripe_head *sh,
3174                    struct stripe_head_state *s)
3175 {
3176         int abort = 0;
3177         int i;
3178
3179         BUG_ON(sh->batch_head);
3180         clear_bit(STRIPE_SYNCING, &sh->state);
3181         if (test_and_clear_bit(R5_Overlap, &sh->dev[sh->pd_idx].flags))
3182                 wake_up(&conf->wait_for_overlap);
3183         s->syncing = 0;
3184         s->replacing = 0;
3185         /* There is nothing more to do for sync/check/repair.
3186          * Don't even need to abort as that is handled elsewhere
3187          * if needed, and not always wanted e.g. if there is a known
3188          * bad block here.
3189          * For recover/replace we need to record a bad block on all
3190          * non-sync devices, or abort the recovery
3191          */
3192         if (test_bit(MD_RECOVERY_RECOVER, &conf->mddev->recovery)) {
3193                 /* During recovery devices cannot be removed, so
3194                  * locking and refcounting of rdevs is not needed
3195                  */
3196                 for (i = 0; i < conf->raid_disks; i++) {
3197                         struct md_rdev *rdev = conf->disks[i].rdev;
3198                         if (rdev
3199                             && !test_bit(Faulty, &rdev->flags)
3200                             && !test_bit(In_sync, &rdev->flags)
3201                             && !rdev_set_badblocks(rdev, sh->sector,
3202                                                    STRIPE_SECTORS, 0))
3203                                 abort = 1;
3204                         rdev = conf->disks[i].replacement;
3205                         if (rdev
3206                             && !test_bit(Faulty, &rdev->flags)
3207                             && !test_bit(In_sync, &rdev->flags)
3208                             && !rdev_set_badblocks(rdev, sh->sector,
3209                                                    STRIPE_SECTORS, 0))
3210                                 abort = 1;
3211                 }
3212                 if (abort)
3213                         conf->recovery_disabled =
3214                                 conf->mddev->recovery_disabled;
3215         }
3216         md_done_sync(conf->mddev, STRIPE_SECTORS, !abort);
3217 }
3218
3219 static int want_replace(struct stripe_head *sh, int disk_idx)
3220 {
3221         struct md_rdev *rdev;
3222         int rv = 0;
3223         /* Doing recovery so rcu locking not required */
3224         rdev = sh->raid_conf->disks[disk_idx].replacement;
3225         if (rdev
3226             && !test_bit(Faulty, &rdev->flags)
3227             && !test_bit(In_sync, &rdev->flags)
3228             && (rdev->recovery_offset <= sh->sector
3229                 || rdev->mddev->recovery_cp <= sh->sector))
3230                 rv = 1;
3231
3232         return rv;
3233 }
3234
3235 /* fetch_block - checks the given member device to see if its data needs
3236  * to be read or computed to satisfy a request.
3237  *
3238  * Returns 1 when no more member devices need to be checked, otherwise returns
3239  * 0 to tell the loop in handle_stripe_fill to continue
3240  */
3241
3242 static int need_this_block(struct stripe_head *sh, struct stripe_head_state *s,
3243                            int disk_idx, int disks)
3244 {
3245         struct r5dev *dev = &sh->dev[disk_idx];
3246         struct r5dev *fdev[2] = { &sh->dev[s->failed_num[0]],
3247                                   &sh->dev[s->failed_num[1]] };
3248         int i;
3249
3250
3251         if (test_bit(R5_LOCKED, &dev->flags) ||
3252             test_bit(R5_UPTODATE, &dev->flags))
3253                 /* No point reading this as we already have it or have
3254                  * decided to get it.
3255                  */
3256                 return 0;
3257
3258         if (dev->toread ||
3259             (dev->towrite && !test_bit(R5_OVERWRITE, &dev->flags)))
3260                 /* We need this block to directly satisfy a request */
3261                 return 1;
3262
3263         if (s->syncing || s->expanding ||
3264             (s->replacing && want_replace(sh, disk_idx)))
3265                 /* When syncing, or expanding we read everything.
3266                  * When replacing, we need the replaced block.
3267                  */
3268                 return 1;
3269
3270         if ((s->failed >= 1 && fdev[0]->toread) ||
3271             (s->failed >= 2 && fdev[1]->toread))
3272                 /* If we want to read from a failed device, then
3273                  * we need to actually read every other device.
3274                  */
3275                 return 1;
3276
3277         /* Sometimes neither read-modify-write nor reconstruct-write
3278          * cycles can work.  In those cases we read every block we
3279          * can.  Then the parity-update is certain to have enough to
3280          * work with.
3281          * This can only be a problem when we need to write something,
3282          * and some device has failed.  If either of those tests
3283          * fail we need look no further.
3284          */
3285         if (!s->failed || !s->to_write)
3286                 return 0;
3287
3288         if (test_bit(R5_Insync, &dev->flags) &&
3289             !test_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
3290                 /* Pre-reads at not permitted until after short delay
3291                  * to gather multiple requests.  However if this
3292                  * device is no Insync, the block could only be be computed
3293                  * and there is no need to delay that.
3294                  */
3295                 return 0;
3296
3297         for (i = 0; i < s->failed; i++) {
3298                 if (fdev[i]->towrite &&
3299                     !test_bit(R5_UPTODATE, &fdev[i]->flags) &&
3300                     !test_bit(R5_OVERWRITE, &fdev[i]->flags))
3301                         /* If we have a partial write to a failed
3302                          * device, then we will need to reconstruct
3303                          * the content of that device, so all other
3304                          * devices must be read.
3305                          */
3306                         return 1;
3307         }
3308
3309         /* If we are forced to do a reconstruct-write, either because
3310          * the current RAID6 implementation only supports that, or
3311          * or because parity cannot be trusted and we are currently
3312          * recovering it, there is extra need to be careful.
3313          * If one of the devices that we would need to read, because
3314          * it is not being overwritten (and maybe not written at all)
3315          * is missing/faulty, then we need to read everything we can.
3316          */
3317         if (sh->raid_conf->level != 6 &&
3318             sh->sector < sh->raid_conf->mddev->recovery_cp)
3319                 /* reconstruct-write isn't being forced */
3320                 return 0;
3321         for (i = 0; i < s->failed; i++) {
3322                 if (s->failed_num[i] != sh->pd_idx &&
3323                     s->failed_num[i] != sh->qd_idx &&
3324                     !test_bit(R5_UPTODATE, &fdev[i]->flags) &&
3325                     !test_bit(R5_OVERWRITE, &fdev[i]->flags))
3326                         return 1;
3327         }
3328
3329         return 0;
3330 }
3331
3332 static int fetch_block(struct stripe_head *sh, struct stripe_head_state *s,
3333                        int disk_idx, int disks)
3334 {
3335         struct r5dev *dev = &sh->dev[disk_idx];
3336
3337         /* is the data in this block needed, and can we get it? */
3338         if (need_this_block(sh, s, disk_idx, disks)) {
3339                 /* we would like to get this block, possibly by computing it,
3340                  * otherwise read it if the backing disk is insync
3341                  */
3342                 BUG_ON(test_bit(R5_Wantcompute, &dev->flags));
3343                 BUG_ON(test_bit(R5_Wantread, &dev->flags));
3344                 BUG_ON(sh->batch_head);
3345                 if ((s->uptodate == disks - 1) &&
3346                     (s->failed && (disk_idx == s->failed_num[0] ||
3347                                    disk_idx == s->failed_num[1]))) {
3348                         /* have disk failed, and we're requested to fetch it;
3349                          * do compute it
3350                          */
3351                         pr_debug("Computing stripe %llu block %d\n",
3352                                (unsigned long long)sh->sector, disk_idx);
3353                         set_bit(STRIPE_COMPUTE_RUN, &sh->state);
3354                         set_bit(STRIPE_OP_COMPUTE_BLK, &s->ops_request);
3355                         set_bit(R5_Wantcompute, &dev->flags);
3356                         sh->ops.target = disk_idx;
3357                         sh->ops.target2 = -1; /* no 2nd target */
3358                         s->req_compute = 1;
3359                         /* Careful: from this point on 'uptodate' is in the eye
3360                          * of raid_run_ops which services 'compute' operations
3361                          * before writes. R5_Wantcompute flags a block that will
3362                          * be R5_UPTODATE by the time it is needed for a
3363                          * subsequent operation.
3364                          */
3365                         s->uptodate++;
3366                         return 1;
3367                 } else if (s->uptodate == disks-2 && s->failed >= 2) {
3368                         /* Computing 2-failure is *very* expensive; only
3369                          * do it if failed >= 2
3370                          */
3371                         int other;
3372                         for (other = disks; other--; ) {
3373                                 if (other == disk_idx)
3374                                         continue;
3375                                 if (!test_bit(R5_UPTODATE,
3376                                       &sh->dev[other].flags))
3377                                         break;
3378                         }
3379                         BUG_ON(other < 0);
3380                         pr_debug("Computing stripe %llu blocks %d,%d\n",
3381                                (unsigned long long)sh->sector,
3382                                disk_idx, other);
3383                         set_bit(STRIPE_COMPUTE_RUN, &sh->state);
3384                         set_bit(STRIPE_OP_COMPUTE_BLK, &s->ops_request);
3385                         set_bit(R5_Wantcompute, &sh->dev[disk_idx].flags);
3386                         set_bit(R5_Wantcompute, &sh->dev[other].flags);
3387                         sh->ops.target = disk_idx;
3388                         sh->ops.target2 = other;
3389                         s->uptodate += 2;
3390                         s->req_compute = 1;
3391                         return 1;
3392                 } else if (test_bit(R5_Insync, &dev->flags)) {
3393                         set_bit(R5_LOCKED, &dev->flags);
3394                         set_bit(R5_Wantread, &dev->flags);
3395                         s->locked++;
3396                         pr_debug("Reading block %d (sync=%d)\n",
3397                                 disk_idx, s->syncing);
3398                 }
3399         }
3400
3401         return 0;
3402 }
3403
3404 /**
3405  * handle_stripe_fill - read or compute data to satisfy pending requests.
3406  */
3407 static void handle_stripe_fill(struct stripe_head *sh,
3408                                struct stripe_head_state *s,
3409                                int disks)
3410 {
3411         int i;
3412
3413         /* look for blocks to read/compute, skip this if a compute
3414          * is already in flight, or if the stripe contents are in the
3415          * midst of changing due to a write
3416          */
3417         if (!test_bit(STRIPE_COMPUTE_RUN, &sh->state) && !sh->check_state &&
3418             !sh->reconstruct_state)
3419                 for (i = disks; i--; )
3420                         if (fetch_block(sh, s, i, disks))
3421                                 break;
3422         set_bit(STRIPE_HANDLE, &sh->state);
3423 }
3424
3425 static void break_stripe_batch_list(struct stripe_head *head_sh,
3426                                     unsigned long handle_flags);
3427 /* handle_stripe_clean_event
3428  * any written block on an uptodate or failed drive can be returned.
3429  * Note that if we 'wrote' to a failed drive, it will be UPTODATE, but
3430  * never LOCKED, so we don't need to test 'failed' directly.
3431  */
3432 static void handle_stripe_clean_event(struct r5conf *conf,
3433         struct stripe_head *sh, int disks, struct bio **return_bi)
3434 {
3435         int i;
3436         struct r5dev *dev;
3437         int discard_pending = 0;
3438         struct stripe_head *head_sh = sh;
3439         bool do_endio = false;
3440
3441         for (i = disks; i--; )
3442                 if (sh->dev[i].written) {
3443                         dev = &sh->dev[i];
3444                         if (!test_bit(R5_LOCKED, &dev->flags) &&
3445                             (test_bit(R5_UPTODATE, &dev->flags) ||
3446                              test_bit(R5_Discard, &dev->flags) ||
3447                              test_bit(R5_SkipCopy, &dev->flags))) {
3448                                 /* We can return any write requests */
3449                                 struct bio *wbi, *wbi2;
3450                                 pr_debug("Return write for disc %d\n", i);
3451                                 if (test_and_clear_bit(R5_Discard, &dev->flags))
3452                                         clear_bit(R5_UPTODATE, &dev->flags);
3453                                 if (test_and_clear_bit(R5_SkipCopy, &dev->flags)) {
3454                                         WARN_ON(test_bit(R5_UPTODATE, &dev->flags));
3455                                 }
3456                                 do_endio = true;
3457
3458 returnbi:
3459                                 dev->page = dev->orig_page;
3460                                 wbi = dev->written;
3461                                 dev->written = NULL;
3462                                 while (wbi && wbi->bi_iter.bi_sector <
3463                                         dev->sector + STRIPE_SECTORS) {
3464                                         wbi2 = r5_next_bio(wbi, dev->sector);
3465                                         if (!raid5_dec_bi_active_stripes(wbi)) {
3466                                                 md_write_end(conf->mddev);
3467                                                 wbi->bi_next = *return_bi;
3468                                                 *return_bi = wbi;
3469                                         }
3470                                         wbi = wbi2;
3471                                 }
3472                                 bitmap_endwrite(conf->mddev->bitmap, sh->sector,
3473                                                 STRIPE_SECTORS,
3474                                          !test_bit(STRIPE_DEGRADED, &sh->state),
3475                                                 0);
3476                                 if (head_sh->batch_head) {
3477                                         sh = list_first_entry(&sh->batch_list,
3478                                                               struct stripe_head,
3479                                                               batch_list);
3480                                         if (sh != head_sh) {
3481                                                 dev = &sh->dev[i];
3482                                                 goto returnbi;
3483                                         }
3484                                 }
3485                                 sh = head_sh;
3486                                 dev = &sh->dev[i];
3487                         } else if (test_bit(R5_Discard, &dev->flags))
3488                                 discard_pending = 1;
3489                         WARN_ON(test_bit(R5_SkipCopy, &dev->flags));
3490                         WARN_ON(dev->page != dev->orig_page);
3491                 }
3492         if (!discard_pending &&
3493             test_bit(R5_Discard, &sh->dev[sh->pd_idx].flags)) {
3494                 clear_bit(R5_Discard, &sh->dev[sh->pd_idx].flags);
3495                 clear_bit(R5_UPTODATE, &sh->dev[sh->pd_idx].flags);
3496                 if (sh->qd_idx >= 0) {
3497                         clear_bit(R5_Discard, &sh->dev[sh->qd_idx].flags);
3498                         clear_bit(R5_UPTODATE, &sh->dev[sh->qd_idx].flags);
3499                 }
3500                 /* now that discard is done we can proceed with any sync */
3501                 clear_bit(STRIPE_DISCARD, &sh->state);
3502                 /*
3503                  * SCSI discard will change some bio fields and the stripe has
3504                  * no updated data, so remove it from hash list and the stripe
3505                  * will be reinitialized
3506                  */
3507                 spin_lock_irq(&conf->device_lock);
3508 unhash:
3509                 remove_hash(sh);
3510                 if (head_sh->batch_head) {
3511                         sh = list_first_entry(&sh->batch_list,
3512                                               struct stripe_head, batch_list);
3513                         if (sh != head_sh)
3514                                         goto unhash;
3515                 }
3516                 spin_unlock_irq(&conf->device_lock);
3517                 sh = head_sh;
3518
3519                 if (test_bit(STRIPE_SYNC_REQUESTED, &sh->state))
3520                         set_bit(STRIPE_HANDLE, &sh->state);
3521
3522         }
3523
3524         if (test_and_clear_bit(STRIPE_FULL_WRITE, &sh->state))
3525                 if (atomic_dec_and_test(&conf->pending_full_writes))
3526                         md_wakeup_thread(conf->mddev->thread);
3527
3528         if (head_sh->batch_head && do_endio)
3529                 break_stripe_batch_list(head_sh, STRIPE_EXPAND_SYNC_FLAGS);
3530 }
3531
3532 static void handle_stripe_dirtying(struct r5conf *conf,
3533                                    struct stripe_head *sh,
3534                                    struct stripe_head_state *s,
3535                                    int disks)
3536 {
3537         int rmw = 0, rcw = 0, i;
3538         sector_t recovery_cp = conf->mddev->recovery_cp;
3539
3540         /* Check whether resync is now happening or should start.
3541          * If yes, then the array is dirty (after unclean shutdown or
3542          * initial creation), so parity in some stripes might be inconsistent.
3543          * In this case, we need to always do reconstruct-write, to ensure
3544          * that in case of drive failure or read-error correction, we
3545          * generate correct data from the parity.
3546          */
3547         if (conf->rmw_level == PARITY_DISABLE_RMW ||
3548             (recovery_cp < MaxSector && sh->sector >= recovery_cp &&
3549              s->failed == 0)) {
3550                 /* Calculate the real rcw later - for now make it
3551                  * look like rcw is cheaper
3552                  */
3553                 rcw = 1; rmw = 2;
3554                 pr_debug("force RCW rmw_level=%u, recovery_cp=%llu sh->sector=%llu\n",
3555                          conf->rmw_level, (unsigned long long)recovery_cp,
3556                          (unsigned long long)sh->sector);
3557         } else for (i = disks; i--; ) {
3558                 /* would I have to read this buffer for read_modify_write */
3559                 struct r5dev *dev = &sh->dev[i];
3560                 if ((dev->towrite || i == sh->pd_idx || i == sh->qd_idx) &&
3561                     !test_bit(R5_LOCKED, &dev->flags) &&
3562                     !(test_bit(R5_UPTODATE, &dev->flags) ||
3563                       test_bit(R5_Wantcompute, &dev->flags))) {
3564                         if (test_bit(R5_Insync, &dev->flags))
3565                                 rmw++;
3566                         else
3567                                 rmw += 2*disks;  /* cannot read it */
3568                 }
3569                 /* Would I have to read this buffer for reconstruct_write */
3570                 if (!test_bit(R5_OVERWRITE, &dev->flags) &&
3571                     i != sh->pd_idx && i != sh->qd_idx &&
3572                     !test_bit(R5_LOCKED, &dev->flags) &&
3573                     !(test_bit(R5_UPTODATE, &dev->flags) ||
3574                     test_bit(R5_Wantcompute, &dev->flags))) {
3575                         if (test_bit(R5_Insync, &dev->flags))
3576                                 rcw++;
3577                         else
3578                                 rcw += 2*disks;
3579                 }
3580         }
3581         pr_debug("for sector %llu, rmw=%d rcw=%d\n",
3582                 (unsigned long long)sh->sector, rmw, rcw);
3583         set_bit(STRIPE_HANDLE, &sh->state);
3584         if ((rmw < rcw || (rmw == rcw && conf->rmw_level == PARITY_ENABLE_RMW)) && rmw > 0) {
3585                 /* prefer read-modify-write, but need to get some data */
3586                 if (conf->mddev->queue)
3587                         blk_add_trace_msg(conf->mddev->queue,
3588                                           "raid5 rmw %llu %d",
3589                                           (unsigned long long)sh->sector, rmw);
3590                 for (i = disks; i--; ) {
3591                         struct r5dev *dev = &sh->dev[i];
3592                         if ((dev->towrite || i == sh->pd_idx || i == sh->qd_idx) &&
3593                             !test_bit(R5_LOCKED, &dev->flags) &&
3594                             !(test_bit(R5_UPTODATE, &dev->flags) ||
3595                             test_bit(R5_Wantcompute, &dev->flags)) &&
3596                             test_bit(R5_Insync, &dev->flags)) {
3597                                 if (test_bit(STRIPE_PREREAD_ACTIVE,
3598                                              &sh->state)) {
3599                                         pr_debug("Read_old block %d for r-m-w\n",
3600                                                  i);
3601                                         set_bit(R5_LOCKED, &dev->flags);
3602                                         set_bit(R5_Wantread, &dev->flags);
3603                                         s->locked++;
3604                                 } else {
3605                                         set_bit(STRIPE_DELAYED, &sh->state);
3606                                         set_bit(STRIPE_HANDLE, &sh->state);
3607                                 }
3608                         }
3609                 }
3610         }
3611         if ((rcw < rmw || (rcw == rmw && conf->rmw_level != PARITY_ENABLE_RMW)) && rcw > 0) {
3612                 /* want reconstruct write, but need to get some data */
3613                 int qread =0;
3614                 rcw = 0;
3615                 for (i = disks; i--; ) {
3616                         struct r5dev *dev = &sh->dev[i];
3617                         if (!test_bit(R5_OVERWRITE, &dev->flags) &&
3618                             i != sh->pd_idx && i != sh->qd_idx &&
3619                             !test_bit(R5_LOCKED, &dev->flags) &&
3620                             !(test_bit(R5_UPTODATE, &dev->flags) ||
3621                               test_bit(R5_Wantcompute, &dev->flags))) {
3622                                 rcw++;
3623                                 if (test_bit(R5_Insync, &dev->flags) &&
3624                                     test_bit(STRIPE_PREREAD_ACTIVE,
3625                                              &sh->state)) {
3626                                         pr_debug("Read_old block "
3627                                                 "%d for Reconstruct\n", i);
3628                                         set_bit(R5_LOCKED, &dev->flags);
3629                                         set_bit(R5_Wantread, &dev->flags);
3630                                         s->locked++;
3631                                         qread++;
3632                                 } else {
3633                                         set_bit(STRIPE_DELAYED, &sh->state);
3634                                         set_bit(STRIPE_HANDLE, &sh->state);
3635                                 }
3636                         }
3637                 }
3638                 if (rcw && conf->mddev->queue)
3639                         blk_add_trace_msg(conf->mddev->queue, "raid5 rcw %llu %d %d %d",
3640                                           (unsigned long long)sh->sector,
3641                                           rcw, qread, test_bit(STRIPE_DELAYED, &sh->state));
3642         }
3643
3644         if (rcw > disks && rmw > disks &&
3645             !test_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
3646                 set_bit(STRIPE_DELAYED, &sh->state);
3647
3648         /* now if nothing is locked, and if we have enough data,
3649          * we can start a write request
3650          */
3651         /* since handle_stripe can be called at any time we need to handle the
3652          * case where a compute block operation has been submitted and then a
3653          * subsequent call wants to start a write request.  raid_run_ops only
3654          * handles the case where compute block and reconstruct are requested
3655          * simultaneously.  If this is not the case then new writes need to be
3656          * held off until the compute completes.
3657          */
3658         if ((s->req_compute || !test_bit(STRIPE_COMPUTE_RUN, &sh->state)) &&
3659             (s->locked == 0 && (rcw == 0 || rmw == 0) &&
3660             !test_bit(STRIPE_BIT_DELAY, &sh->state)))
3661                 schedule_reconstruction(sh, s, rcw == 0, 0);
3662 }
3663
3664 static void handle_parity_checks5(struct r5conf *conf, struct stripe_head *sh,
3665                                 struct stripe_head_state *s, int disks)
3666 {
3667         struct r5dev *dev = NULL;
3668
3669         BUG_ON(sh->batch_head);
3670         set_bit(STRIPE_HANDLE, &sh->state);
3671
3672         switch (sh->check_state) {
3673         case check_state_idle:
3674                 /* start a new check operation if there are no failures */
3675                 if (s->failed == 0) {
3676                         BUG_ON(s->uptodate != disks);
3677                         sh->check_state = check_state_run;
3678                         set_bit(STRIPE_OP_CHECK, &s->ops_request);
3679                         clear_bit(R5_UPTODATE, &sh->dev[sh->pd_idx].flags);
3680                         s->uptodate--;
3681                         break;
3682                 }
3683                 dev = &sh->dev[s->failed_num[0]];
3684                 /* fall through */
3685         case check_state_compute_result:
3686                 sh->check_state = check_state_idle;
3687                 if (!dev)
3688                         dev = &sh->dev[sh->pd_idx];
3689
3690                 /* check that a write has not made the stripe insync */
3691                 if (test_bit(STRIPE_INSYNC, &sh->state))
3692                         break;
3693
3694                 /* either failed parity check, or recovery is happening */
3695                 BUG_ON(!test_bit(R5_UPTODATE, &dev->flags));
3696                 BUG_ON(s->uptodate != disks);
3697
3698                 set_bit(R5_LOCKED, &dev->flags);
3699                 s->locked++;
3700                 set_bit(R5_Wantwrite, &dev->flags);
3701
3702                 clear_bit(STRIPE_DEGRADED, &sh->state);
3703                 set_bit(STRIPE_INSYNC, &sh->state);
3704                 break;
3705         case check_state_run:
3706                 break; /* we will be called again upon completion */
3707         case check_state_check_result:
3708                 sh->check_state = check_state_idle;
3709
3710                 /* if a failure occurred during the check operation, leave
3711                  * STRIPE_INSYNC not set and let the stripe be handled again
3712                  */
3713                 if (s->failed)
3714                         break;
3715
3716                 /* handle a successful check operation, if parity is correct
3717                  * we are done.  Otherwise update the mismatch count and repair
3718                  * parity if !MD_RECOVERY_CHECK
3719                  */
3720                 if ((sh->ops.zero_sum_result & SUM_CHECK_P_RESULT) == 0)
3721                         /* parity is correct (on disc,
3722                          * not in buffer any more)
3723                          */
3724                         set_bit(STRIPE_INSYNC, &sh->state);
3725                 else {
3726                         atomic64_add(STRIPE_SECTORS, &conf->mddev->resync_mismatches);
3727                         if (test_bit(MD_RECOVERY_CHECK, &conf->mddev->recovery))
3728                                 /* don't try to repair!! */
3729                                 set_bit(STRIPE_INSYNC, &sh->state);
3730                         else {
3731                                 sh->check_state = check_state_compute_run;
3732                                 set_bit(STRIPE_COMPUTE_RUN, &sh->state);
3733                                 set_bit(STRIPE_OP_COMPUTE_BLK, &s->ops_request);
3734                                 set_bit(R5_Wantcompute,
3735                                         &sh->dev[sh->pd_idx].flags);
3736                                 sh->ops.target = sh->pd_idx;
3737                                 sh->ops.target2 = -1;
3738                                 s->uptodate++;
3739                         }
3740                 }
3741                 break;
3742         case check_state_compute_run:
3743                 break;
3744         default:
3745                 printk(KERN_ERR "%s: unknown check_state: %d sector: %llu\n",
3746                        __func__, sh->check_state,
3747                        (unsigned long long) sh->sector);
3748                 BUG();
3749         }
3750 }
3751
3752 static void handle_parity_checks6(struct r5conf *conf, struct stripe_head *sh,
3753                                   struct stripe_head_state *s,
3754                                   int disks)
3755 {
3756         int pd_idx = sh->pd_idx;
3757         int qd_idx = sh->qd_idx;
3758         struct r5dev *dev;
3759
3760         BUG_ON(sh->batch_head);
3761         set_bit(STRIPE_HANDLE, &sh->state);
3762
3763         BUG_ON(s->failed > 2);
3764
3765         /* Want to check and possibly repair P and Q.
3766          * However there could be one 'failed' device, in which
3767          * case we can only check one of them, possibly using the
3768          * other to generate missing data
3769          */
3770
3771         switch (sh->check_state) {
3772         case check_state_idle:
3773                 /* start a new check operation if there are < 2 failures */
3774                 if (s->failed == s->q_failed) {
3775                         /* The only possible failed device holds Q, so it
3776                          * makes sense to check P (If anything else were failed,
3777                          * we would have used P to recreate it).
3778                          */
3779                         sh->check_state = check_state_run;
3780                 }
3781                 if (!s->q_failed && s->failed < 2) {
3782                         /* Q is not failed, and we didn't use it to generate
3783                          * anything, so it makes sense to check it
3784                          */
3785                         if (sh->check_state == check_state_run)
3786                                 sh->check_state = check_state_run_pq;
3787                         else
3788                                 sh->check_state = check_state_run_q;
3789                 }
3790
3791                 /* discard potentially stale zero_sum_result */
3792                 sh->ops.zero_sum_result = 0;
3793
3794                 if (sh->check_state == check_state_run) {
3795                         /* async_xor_zero_sum destroys the contents of P */
3796                         clear_bit(R5_UPTODATE, &sh->dev[pd_idx].flags);
3797                         s->uptodate--;
3798                 }
3799                 if (sh->check_state >= check_state_run &&
3800                     sh->check_state <= check_state_run_pq) {
3801                         /* async_syndrome_zero_sum preserves P and Q, so
3802                          * no need to mark them !uptodate here
3803                          */
3804                         set_bit(STRIPE_OP_CHECK, &s->ops_request);
3805                         break;
3806                 }
3807
3808                 /* we have 2-disk failure */
3809                 BUG_ON(s->failed != 2);
3810                 /* fall through */
3811         case check_state_compute_result:
3812                 sh->check_state = check_state_idle;
3813
3814                 /* check that a write has not made the stripe insync */
3815                 if (test_bit(STRIPE_INSYNC, &sh->state))
3816                         break;
3817
3818                 /* now write out any block on a failed drive,
3819                  * or P or Q if they were recomputed
3820                  */
3821                 BUG_ON(s->uptodate < disks - 1); /* We don't need Q to recover */
3822                 if (s->failed == 2) {
3823                         dev = &sh->dev[s->failed_num[1]];
3824                         s->locked++;
3825                         set_bit(R5_LOCKED, &dev->flags);
3826                         set_bit(R5_Wantwrite, &dev->flags);
3827                 }
3828                 if (s->failed >= 1) {
3829                         dev = &sh->dev[s->failed_num[0]];
3830                         s->locked++;
3831                         set_bit(R5_LOCKED, &dev->flags);
3832                         set_bit(R5_Wantwrite, &dev->flags);
3833                 }
3834                 if (sh->ops.zero_sum_result & SUM_CHECK_P_RESULT) {
3835                         dev = &sh->dev[pd_idx];
3836                         s->locked++;
3837                         set_bit(R5_LOCKED, &dev->flags);
3838                         set_bit(R5_Wantwrite, &dev->flags);
3839                 }
3840                 if (sh->ops.zero_sum_result & SUM_CHECK_Q_RESULT) {
3841                         dev = &sh->dev[qd_idx];
3842                         s->locked++;
3843                         set_bit(R5_LOCKED, &dev->flags);
3844                         set_bit(R5_Wantwrite, &dev->flags);
3845                 }
3846                 clear_bit(STRIPE_DEGRADED, &sh->state);
3847
3848                 set_bit(STRIPE_INSYNC, &sh->state);
3849                 break;
3850         case check_state_run:
3851         case check_state_run_q:
3852         case check_state_run_pq:
3853                 break; /* we will be called again upon completion */
3854         case check_state_check_result:
3855                 sh->check_state = check_state_idle;
3856
3857                 /* handle a successful check operation, if parity is correct
3858                  * we are done.  Otherwise update the mismatch count and repair
3859                  * parity if !MD_RECOVERY_CHECK
3860                  */
3861                 if (sh->ops.zero_sum_result == 0) {
3862                         /* both parities are correct */
3863                         if (!s->failed)
3864                                 set_bit(STRIPE_INSYNC, &sh->state);
3865                         else {
3866                                 /* in contrast to the raid5 case we can validate
3867                                  * parity, but still have a failure to write
3868                                  * back
3869                                  */
3870                                 sh->check_state = check_state_compute_result;
3871                                 /* Returning at this point means that we may go
3872                                  * off and bring p and/or q uptodate again so
3873                                  * we make sure to check zero_sum_result again
3874                                  * to verify if p or q need writeback
3875                                  */
3876                         }
3877                 } else {
3878                         atomic64_add(STRIPE_SECTORS, &conf->mddev->resync_mismatches);
3879                         if (test_bit(MD_RECOVERY_CHECK, &conf->mddev->recovery))
3880                                 /* don't try to repair!! */
3881                                 set_bit(STRIPE_INSYNC, &sh->state);
3882                         else {
3883                                 int *target = &sh->ops.target;
3884
3885                                 sh->ops.target = -1;
3886                                 sh->ops.target2 = -1;
3887                                 sh->check_state = check_state_compute_run;
3888                                 set_bit(STRIPE_COMPUTE_RUN, &sh->state);
3889                                 set_bit(STRIPE_OP_COMPUTE_BLK, &s->ops_request);
3890                                 if (sh->ops.zero_sum_result & SUM_CHECK_P_RESULT) {
3891                                         set_bit(R5_Wantcompute,
3892                                                 &sh->dev[pd_idx].flags);
3893                                         *target = pd_idx;
3894                                         target = &sh->ops.target2;
3895                                         s->uptodate++;
3896                                 }
3897                                 if (sh->ops.zero_sum_result & SUM_CHECK_Q_RESULT) {
3898                                         set_bit(R5_Wantcompute,
3899                                                 &sh->dev[qd_idx].flags);
3900                                         *target = qd_idx;
3901                                         s->uptodate++;
3902                                 }
3903                         }
3904                 }
3905                 break;
3906         case check_state_compute_run:
3907                 break;
3908         default:
3909                 printk(KERN_ERR "%s: unknown check_state: %d sector: %llu\n",
3910                        __func__, sh->check_state,
3911                        (unsigned long long) sh->sector);
3912                 BUG();
3913         }
3914 }
3915
3916 static void handle_stripe_expansion(struct r5conf *conf, struct stripe_head *sh)
3917 {
3918         int i;
3919
3920         /* We have read all the blocks in this stripe and now we need to
3921          * copy some of them into a target stripe for expand.
3922          */
3923         struct dma_async_tx_descriptor *tx = NULL;
3924         BUG_ON(sh->batch_head);
3925         clear_bit(STRIPE_EXPAND_SOURCE, &sh->state);
3926         for (i = 0; i < sh->disks; i++)
3927                 if (i != sh->pd_idx && i != sh->qd_idx) {
3928                         int dd_idx, j;
3929                         struct stripe_head *sh2;
3930                         struct async_submit_ctl submit;
3931
3932                         sector_t bn = compute_blocknr(sh, i, 1);
3933                         sector_t s = raid5_compute_sector(conf, bn, 0,
3934                                                           &dd_idx, NULL);
3935                         sh2 = get_active_stripe(conf, s, 0, 1, 1);
3936                         if (sh2 == NULL)
3937                                 /* so far only the early blocks of this stripe
3938                                  * have been requested.  When later blocks
3939                                  * get requested, we will try again
3940                                  */
3941                                 continue;
3942                         if (!test_bit(STRIPE_EXPANDING, &sh2->state) ||
3943                            test_bit(R5_Expanded, &sh2->dev[dd_idx].flags)) {
3944                                 /* must have already done this block */
3945                                 release_stripe(sh2);
3946                                 continue;
3947                         }
3948
3949                         /* place all the copies on one channel */
3950                         init_async_submit(&submit, 0, tx, NULL, NULL, NULL);
3951                         tx = async_memcpy(sh2->dev[dd_idx].page,
3952                                           sh->dev[i].page, 0, 0, STRIPE_SIZE,
3953                                           &submit);
3954
3955                         set_bit(R5_Expanded, &sh2->dev[dd_idx].flags);
3956                         set_bit(R5_UPTODATE, &sh2->dev[dd_idx].flags);
3957                         for (j = 0; j < conf->raid_disks; j++)
3958                                 if (j != sh2->pd_idx &&
3959                                     j != sh2->qd_idx &&
3960                                     !test_bit(R5_Expanded, &sh2->dev[j].flags))
3961                                         break;
3962                         if (j == conf->raid_disks) {
3963                                 set_bit(STRIPE_EXPAND_READY, &sh2->state);
3964                                 set_bit(STRIPE_HANDLE, &sh2->state);
3965                         }
3966                         release_stripe(sh2);
3967
3968                 }
3969         /* done submitting copies, wait for them to complete */
3970         async_tx_quiesce(&tx);
3971 }
3972
3973 /*
3974  * handle_stripe - do things to a stripe.
3975  *
3976  * We lock the stripe by setting STRIPE_ACTIVE and then examine the
3977  * state of various bits to see what needs to be done.
3978  * Possible results:
3979  *    return some read requests which now have data
3980  *    return some write requests which are safely on storage
3981  *    schedule a read on some buffers
3982  *    schedule a write of some buffers
3983  *    return confirmation of parity correctness
3984  *
3985  */
3986
3987 static void analyse_stripe(struct stripe_head *sh, struct stripe_head_state *s)
3988 {
3989         struct r5conf *conf = sh->raid_conf;
3990         int disks = sh->disks;
3991         struct r5dev *dev;
3992         int i;
3993         int do_recovery = 0;
3994
3995         memset(s, 0, sizeof(*s));
3996
3997         s->expanding = test_bit(STRIPE_EXPAND_SOURCE, &sh->state) && !sh->batch_head;
3998         s->expanded = test_bit(STRIPE_EXPAND_READY, &sh->state) && !sh->batch_head;
3999         s->failed_num[0] = -1;
4000         s->failed_num[1] = -1;
4001
4002         /* Now to look around and see what can be done */
4003         rcu_read_lock();
4004         for (i=disks; i--; ) {
4005                 struct md_rdev *rdev;
4006                 sector_t first_bad;
4007                 int bad_sectors;
4008                 int is_bad = 0;
4009
4010                 dev = &sh->dev[i];
4011
4012                 pr_debug("check %d: state 0x%lx read %p write %p written %p\n",
4013                          i, dev->flags,
4014                          dev->toread, dev->towrite, dev->written);
4015                 /* maybe we can reply to a read
4016                  *
4017                  * new wantfill requests are only permitted while
4018                  * ops_complete_biofill is guaranteed to be inactive
4019                  */
4020                 if (test_bit(R5_UPTODATE, &dev->flags) && dev->toread &&
4021                     !test_bit(STRIPE_BIOFILL_RUN, &sh->state))
4022                         set_bit(R5_Wantfill, &dev->flags);
4023
4024                 /* now count some things */
4025                 if (test_bit(R5_LOCKED, &dev->flags))
4026                         s->locked++;
4027                 if (test_bit(R5_UPTODATE, &dev->flags))
4028                         s->uptodate++;
4029                 if (test_bit(R5_Wantcompute, &dev->flags)) {
4030                         s->compute++;
4031                         BUG_ON(s->compute > 2);
4032                 }
4033
4034                 if (test_bit(R5_Wantfill, &dev->flags))
4035                         s->to_fill++;
4036                 else if (dev->toread)
4037                         s->to_read++;
4038                 if (dev->towrite) {
4039                         s->to_write++;
4040                         if (!test_bit(R5_OVERWRITE, &dev->flags))
4041                                 s->non_overwrite++;
4042                 }
4043                 if (dev->written)
4044                         s->written++;
4045                 /* Prefer to use the replacement for reads, but only
4046                  * if it is recovered enough and has no bad blocks.
4047                  */
4048                 rdev = rcu_dereference(conf->disks[i].replacement);
4049                 if (rdev && !test_bit(Faulty, &rdev->flags) &&
4050                     rdev->recovery_offset >= sh->sector + STRIPE_SECTORS &&
4051                     !is_badblock(rdev, sh->sector, STRIPE_SECTORS,
4052                                  &first_bad, &bad_sectors))
4053                         set_bit(R5_ReadRepl, &dev->flags);
4054                 else {
4055                         if (rdev)
4056                                 set_bit(R5_NeedReplace, &dev->flags);
4057                         rdev = rcu_dereference(conf->disks[i].rdev);
4058                         clear_bit(R5_ReadRepl, &dev->flags);
4059                 }
4060                 if (rdev && test_bit(Faulty, &rdev->flags))
4061                         rdev = NULL;
4062                 if (rdev) {
4063                         is_bad = is_badblock(rdev, sh->sector, STRIPE_SECTORS,
4064                                              &first_bad, &bad_sectors);
4065                         if (s->blocked_rdev == NULL
4066                             && (test_bit(Blocked, &rdev->flags)
4067                                 || is_bad < 0)) {
4068                                 if (is_bad < 0)
4069                                         set_bit(BlockedBadBlocks,
4070                                                 &rdev->flags);
4071                                 s->blocked_rdev = rdev;
4072                                 atomic_inc(&rdev->nr_pending);
4073                         }
4074                 }
4075                 clear_bit(R5_Insync, &dev->flags);
4076                 if (!rdev)
4077                         /* Not in-sync */;
4078                 else if (is_bad) {
4079                         /* also not in-sync */
4080                         if (!test_bit(WriteErrorSeen, &rdev->flags) &&
4081                             test_bit(R5_UPTODATE, &dev->flags)) {
4082                                 /* treat as in-sync, but with a read error
4083                                  * which we can now try to correct
4084                                  */
4085                                 set_bit(R5_Insync, &dev->flags);
4086                                 set_bit(R5_ReadError, &dev->flags);
4087                         }
4088                 } else if (test_bit(In_sync, &rdev->flags))
4089                         set_bit(R5_Insync, &dev->flags);
4090                 else if (sh->sector + STRIPE_SECTORS <= rdev->recovery_offset)
4091                         /* in sync if before recovery_offset */
4092                         set_bit(R5_Insync, &dev->flags);
4093                 else if (test_bit(R5_UPTODATE, &dev->flags) &&
4094                          test_bit(R5_Expanded, &dev->flags))
4095                         /* If we've reshaped into here, we assume it is Insync.
4096                          * We will shortly update recovery_offset to make
4097                          * it official.
4098                          */
4099                         set_bit(R5_Insync, &dev->flags);
4100
4101                 if (test_bit(R5_WriteError, &dev->flags)) {
4102                         /* This flag does not apply to '.replacement'
4103                          * only to .rdev, so make sure to check that*/
4104                         struct md_rdev *rdev2 = rcu_dereference(
4105                                 conf->disks[i].rdev);
4106                         if (rdev2 == rdev)
4107                                 clear_bit(R5_Insync, &dev->flags);
4108                         if (rdev2 && !test_bit(Faulty, &rdev2->flags)) {
4109                                 s->handle_bad_blocks = 1;
4110                                 atomic_inc(&rdev2->nr_pending);
4111                         } else
4112                                 clear_bit(R5_WriteError, &dev->flags);
4113                 }
4114                 if (test_bit(R5_MadeGood, &dev->flags)) {
4115                         /* This flag does not apply to '.replacement'
4116                          * only to .rdev, so make sure to check that*/
4117                         struct md_rdev *rdev2 = rcu_dereference(
4118                                 conf->disks[i].rdev);
4119                         if (rdev2 && !test_bit(Faulty, &rdev2->flags)) {
4120                                 s->handle_bad_blocks = 1;
4121                                 atomic_inc(&rdev2->nr_pending);
4122                         } else
4123                                 clear_bit(R5_MadeGood, &dev->flags);
4124                 }
4125                 if (test_bit(R5_MadeGoodRepl, &dev->flags)) {
4126                         struct md_rdev *rdev2 = rcu_dereference(
4127                                 conf->disks[i].replacement);
4128                         if (rdev2 && !test_bit(Faulty, &rdev2->flags)) {
4129                                 s->handle_bad_blocks = 1;
4130                                 atomic_inc(&rdev2->nr_pending);
4131                         } else
4132                                 clear_bit(R5_MadeGoodRepl, &dev->flags);
4133                 }
4134                 if (!test_bit(R5_Insync, &dev->flags)) {
4135                         /* The ReadError flag will just be confusing now */
4136                         clear_bit(R5_ReadError, &dev->flags);
4137                         clear_bit(R5_ReWrite, &dev->flags);
4138                 }
4139                 if (test_bit(R5_ReadError, &dev->flags))
4140                         clear_bit(R5_Insync, &dev->flags);
4141                 if (!test_bit(R5_Insync, &dev->flags)) {
4142                         if (s->failed < 2)
4143                                 s->failed_num[s->failed] = i;
4144                         s->failed++;
4145                         if (rdev && !test_bit(Faulty, &rdev->flags))
4146                                 do_recovery = 1;
4147                 }
4148         }
4149         if (test_bit(STRIPE_SYNCING, &sh->state)) {
4150                 /* If there is a failed device being replaced,
4151                  *     we must be recovering.
4152                  * else if we are after recovery_cp, we must be syncing
4153                  * else if MD_RECOVERY_REQUESTED is set, we also are syncing.
4154                  * else we can only be replacing
4155                  * sync and recovery both need to read all devices, and so
4156                  * use the same flag.
4157                  */
4158                 if (do_recovery ||
4159                     sh->sector >= conf->mddev->recovery_cp ||
4160                     test_bit(MD_RECOVERY_REQUESTED, &(conf->mddev->recovery)))
4161                         s->syncing = 1;
4162                 else
4163                         s->replacing = 1;
4164         }
4165         rcu_read_unlock();
4166 }
4167
4168 static int clear_batch_ready(struct stripe_head *sh)
4169 {
4170         /* Return '1' if this is a member of batch, or
4171          * '0' if it is a lone stripe or a head which can now be
4172          * handled.
4173          */
4174         struct stripe_head *tmp;
4175         if (!test_and_clear_bit(STRIPE_BATCH_READY, &sh->state))
4176                 return (sh->batch_head && sh->batch_head != sh);
4177         spin_lock(&sh->stripe_lock);
4178         if (!sh->batch_head) {
4179                 spin_unlock(&sh->stripe_lock);
4180                 return 0;
4181         }
4182
4183         /*
4184          * this stripe could be added to a batch list before we check
4185          * BATCH_READY, skips it
4186          */
4187         if (sh->batch_head != sh) {
4188                 spin_unlock(&sh->stripe_lock);
4189                 return 1;
4190         }
4191         spin_lock(&sh->batch_lock);
4192         list_for_each_entry(tmp, &sh->batch_list, batch_list)
4193                 clear_bit(STRIPE_BATCH_READY, &tmp->state);
4194         spin_unlock(&sh->batch_lock);
4195         spin_unlock(&sh->stripe_lock);
4196
4197         /*
4198          * BATCH_READY is cleared, no new stripes can be added.
4199          * batch_list can be accessed without lock
4200          */
4201         return 0;
4202 }
4203
4204 static void break_stripe_batch_list(struct stripe_head *head_sh,
4205                                     unsigned long handle_flags)
4206 {
4207         struct stripe_head *sh, *next;
4208         int i;
4209         int do_wakeup = 0;
4210
4211         list_for_each_entry_safe(sh, next, &head_sh->batch_list, batch_list) {
4212
4213                 list_del_init(&sh->batch_list);
4214
4215                 WARN_ON_ONCE(sh->state & ((1 << STRIPE_ACTIVE) |
4216                                           (1 << STRIPE_SYNCING) |
4217                                           (1 << STRIPE_REPLACED) |
4218                                           (1 << STRIPE_PREREAD_ACTIVE) |
4219                                           (1 << STRIPE_DELAYED) |
4220                                           (1 << STRIPE_BIT_DELAY) |
4221                                           (1 << STRIPE_FULL_WRITE) |
4222                                           (1 << STRIPE_BIOFILL_RUN) |
4223                                           (1 << STRIPE_COMPUTE_RUN)  |
4224                                           (1 << STRIPE_OPS_REQ_PENDING) |
4225                                           (1 << STRIPE_DISCARD) |
4226                                           (1 << STRIPE_BATCH_READY) |
4227                                           (1 << STRIPE_BATCH_ERR) |
4228                                           (1 << STRIPE_BITMAP_PENDING)));
4229                 WARN_ON_ONCE(head_sh->state & ((1 << STRIPE_DISCARD) |
4230                                               (1 << STRIPE_REPLACED)));
4231
4232                 set_mask_bits(&sh->state, ~(STRIPE_EXPAND_SYNC_FLAGS |
4233                                             (1 << STRIPE_DEGRADED)),
4234                               head_sh->state & (1 << STRIPE_INSYNC));
4235
4236                 sh->check_state = head_sh->check_state;
4237                 sh->reconstruct_state = head_sh->reconstruct_state;
4238                 for (i = 0; i < sh->disks; i++) {
4239                         if (test_and_clear_bit(R5_Overlap, &sh->dev[i].flags))
4240                                 do_wakeup = 1;
4241                         sh->dev[i].flags = head_sh->dev[i].flags &
4242                                 (~((1 << R5_WriteError) | (1 << R5_Overlap)));
4243                 }
4244                 spin_lock_irq(&sh->stripe_lock);
4245                 sh->batch_head = NULL;
4246                 spin_unlock_irq(&sh->stripe_lock);
4247                 if (handle_flags == 0 ||
4248                     sh->state & handle_flags)
4249                         set_bit(STRIPE_HANDLE, &sh->state);
4250                 release_stripe(sh);
4251         }
4252         spin_lock_irq(&head_sh->stripe_lock);
4253         head_sh->batch_head = NULL;
4254         spin_unlock_irq(&head_sh->stripe_lock);
4255         for (i = 0; i < head_sh->disks; i++)
4256                 if (test_and_clear_bit(R5_Overlap, &head_sh->dev[i].flags))
4257                         do_wakeup = 1;
4258         if (head_sh->state & handle_flags)
4259                 set_bit(STRIPE_HANDLE, &head_sh->state);
4260
4261         if (do_wakeup)
4262                 wake_up(&head_sh->raid_conf->wait_for_overlap);
4263 }
4264
4265 static void handle_stripe(struct stripe_head *sh)
4266 {
4267         struct stripe_head_state s;
4268         struct r5conf *conf = sh->raid_conf;
4269         int i;
4270         int prexor;
4271         int disks = sh->disks;
4272         struct r5dev *pdev, *qdev;
4273
4274         clear_bit(STRIPE_HANDLE, &sh->state);
4275         if (test_and_set_bit_lock(STRIPE_ACTIVE, &sh->state)) {
4276                 /* already being handled, ensure it gets handled
4277                  * again when current action finishes */
4278                 set_bit(STRIPE_HANDLE, &sh->state);
4279                 return;
4280         }
4281
4282         if (clear_batch_ready(sh) ) {
4283                 clear_bit_unlock(STRIPE_ACTIVE, &sh->state);
4284                 return;
4285         }
4286
4287         if (test_and_clear_bit(STRIPE_BATCH_ERR, &sh->state))
4288                 break_stripe_batch_list(sh, 0);
4289
4290         if (test_bit(STRIPE_SYNC_REQUESTED, &sh->state) && !sh->batch_head) {
4291                 spin_lock(&sh->stripe_lock);
4292                 /* Cannot process 'sync' concurrently with 'discard' */
4293                 if (!test_bit(STRIPE_DISCARD, &sh->state) &&
4294                     test_and_clear_bit(STRIPE_SYNC_REQUESTED, &sh->state)) {
4295                         set_bit(STRIPE_SYNCING, &sh->state);
4296                         clear_bit(STRIPE_INSYNC, &sh->state);
4297                         clear_bit(STRIPE_REPLACED, &sh->state);
4298                 }
4299                 spin_unlock(&sh->stripe_lock);
4300         }
4301         clear_bit(STRIPE_DELAYED, &sh->state);
4302
4303         pr_debug("handling stripe %llu, state=%#lx cnt=%d, "
4304                 "pd_idx=%d, qd_idx=%d\n, check:%d, reconstruct:%d\n",
4305                (unsigned long long)sh->sector, sh->state,
4306                atomic_read(&sh->count), sh->pd_idx, sh->qd_idx,
4307                sh->check_state, sh->reconstruct_state);
4308
4309         analyse_stripe(sh, &s);
4310
4311         if (s.handle_bad_blocks) {
4312                 set_bit(STRIPE_HANDLE, &sh->state);
4313                 goto finish;
4314         }
4315
4316         if (unlikely(s.blocked_rdev)) {
4317                 if (s.syncing || s.expanding || s.expanded ||
4318                     s.replacing || s.to_write || s.written) {
4319                         set_bit(STRIPE_HANDLE, &sh->state);
4320                         goto finish;
4321                 }
4322                 /* There is nothing for the blocked_rdev to block */
4323                 rdev_dec_pending(s.blocked_rdev, conf->mddev);
4324                 s.blocked_rdev = NULL;
4325         }
4326
4327         if (s.to_fill && !test_bit(STRIPE_BIOFILL_RUN, &sh->state)) {
4328                 set_bit(STRIPE_OP_BIOFILL, &s.ops_request);
4329                 set_bit(STRIPE_BIOFILL_RUN, &sh->state);
4330         }
4331
4332         pr_debug("locked=%d uptodate=%d to_read=%d"
4333                " to_write=%d failed=%d failed_num=%d,%d\n",
4334                s.locked, s.uptodate, s.to_read, s.to_write, s.failed,
4335                s.failed_num[0], s.failed_num[1]);
4336         /* check if the array has lost more than max_degraded devices and,
4337          * if so, some requests might need to be failed.
4338          */
4339         if (s.failed > conf->max_degraded) {
4340                 sh->check_state = 0;
4341                 sh->reconstruct_state = 0;
4342                 break_stripe_batch_list(sh, 0);
4343                 if (s.to_read+s.to_write+s.written)
4344                         handle_failed_stripe(conf, sh, &s, disks, &s.return_bi);
4345                 if (s.syncing + s.replacing)
4346                         handle_failed_sync(conf, sh, &s);
4347         }
4348
4349         /* Now we check to see if any write operations have recently
4350          * completed
4351          */
4352         prexor = 0;
4353         if (sh->reconstruct_state == reconstruct_state_prexor_drain_result)
4354                 prexor = 1;
4355         if (sh->reconstruct_state == reconstruct_state_drain_result ||
4356             sh->reconstruct_state == reconstruct_state_prexor_drain_result) {
4357                 sh->reconstruct_state = reconstruct_state_idle;
4358
4359                 /* All the 'written' buffers and the parity block are ready to
4360                  * be written back to disk
4361                  */
4362                 BUG_ON(!test_bit(R5_UPTODATE, &sh->dev[sh->pd_idx].flags) &&
4363                        !test_bit(R5_Discard, &sh->dev[sh->pd_idx].flags));
4364                 BUG_ON(sh->qd_idx >= 0 &&
4365                        !test_bit(R5_UPTODATE, &sh->dev[sh->qd_idx].flags) &&
4366                        !test_bit(R5_Discard, &sh->dev[sh->qd_idx].flags));
4367                 for (i = disks; i--; ) {
4368                         struct r5dev *dev = &sh->dev[i];
4369                         if (test_bit(R5_LOCKED, &dev->flags) &&
4370                                 (i == sh->pd_idx || i == sh->qd_idx ||
4371                                  dev->written)) {
4372                                 pr_debug("Writing block %d\n", i);
4373                                 set_bit(R5_Wantwrite, &dev->flags);
4374                                 if (prexor)
4375                                         continue;
4376                                 if (s.failed > 1)
4377                                         continue;
4378                                 if (!test_bit(R5_Insync, &dev->flags) ||
4379                                     ((i == sh->pd_idx || i == sh->qd_idx)  &&
4380                                      s.failed == 0))
4381                                         set_bit(STRIPE_INSYNC, &sh->state);
4382                         }
4383                 }
4384                 if (test_and_clear_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
4385                         s.dec_preread_active = 1;
4386         }
4387
4388         /*
4389          * might be able to return some write requests if the parity blocks
4390          * are safe, or on a failed drive
4391          */
4392         pdev = &sh->dev[sh->pd_idx];
4393         s.p_failed = (s.failed >= 1 && s.failed_num[0] == sh->pd_idx)
4394                 || (s.failed >= 2 && s.failed_num[1] == sh->pd_idx);
4395         qdev = &sh->dev[sh->qd_idx];
4396         s.q_failed = (s.failed >= 1 && s.failed_num[0] == sh->qd_idx)
4397                 || (s.failed >= 2 && s.failed_num[1] == sh->qd_idx)
4398                 || conf->level < 6;
4399
4400         if (s.written &&
4401             (s.p_failed || ((test_bit(R5_Insync, &pdev->flags)
4402                              && !test_bit(R5_LOCKED, &pdev->flags)
4403                              && (test_bit(R5_UPTODATE, &pdev->flags) ||
4404                                  test_bit(R5_Discard, &pdev->flags))))) &&
4405             (s.q_failed || ((test_bit(R5_Insync, &qdev->flags)
4406                              && !test_bit(R5_LOCKED, &qdev->flags)
4407                              && (test_bit(R5_UPTODATE, &qdev->flags) ||
4408                                  test_bit(R5_Discard, &qdev->flags))))))
4409                 handle_stripe_clean_event(conf, sh, disks, &s.return_bi);
4410
4411         /* Now we might consider reading some blocks, either to check/generate
4412          * parity, or to satisfy requests
4413          * or to load a block that is being partially written.
4414          */
4415         if (s.to_read || s.non_overwrite
4416             || (conf->level == 6 && s.to_write && s.failed)
4417             || (s.syncing && (s.uptodate + s.compute < disks))
4418             || s.replacing
4419             || s.expanding)
4420                 handle_stripe_fill(sh, &s, disks);
4421
4422         /* Now to consider new write requests and what else, if anything
4423          * should be read.  We do not handle new writes when:
4424          * 1/ A 'write' operation (copy+xor) is already in flight.
4425          * 2/ A 'check' operation is in flight, as it may clobber the parity
4426          *    block.
4427          */
4428         if (s.to_write && !sh->reconstruct_state && !sh->check_state)
4429                 handle_stripe_dirtying(conf, sh, &s, disks);
4430
4431         /* maybe we need to check and possibly fix the parity for this stripe
4432          * Any reads will already have been scheduled, so we just see if enough
4433          * data is available.  The parity check is held off while parity
4434          * dependent operations are in flight.
4435          */
4436         if (sh->check_state ||
4437             (s.syncing && s.locked == 0 &&
4438              !test_bit(STRIPE_COMPUTE_RUN, &sh->state) &&
4439              !test_bit(STRIPE_INSYNC, &sh->state))) {
4440                 if (conf->level == 6)
4441                         handle_parity_checks6(conf, sh, &s, disks);
4442                 else
4443                         handle_parity_checks5(conf, sh, &s, disks);
4444         }
4445
4446         if ((s.replacing || s.syncing) && s.locked == 0
4447             && !test_bit(STRIPE_COMPUTE_RUN, &sh->state)
4448             && !test_bit(STRIPE_REPLACED, &sh->state)) {
4449                 /* Write out to replacement devices where possible */
4450                 for (i = 0; i < conf->raid_disks; i++)
4451                         if (test_bit(R5_NeedReplace, &sh->dev[i].flags)) {
4452                                 WARN_ON(!test_bit(R5_UPTODATE, &sh->dev[i].flags));
4453                                 set_bit(R5_WantReplace, &sh->dev[i].flags);
4454                                 set_bit(R5_LOCKED, &sh->dev[i].flags);
4455                                 s.locked++;
4456                         }
4457                 if (s.replacing)
4458                         set_bit(STRIPE_INSYNC, &sh->state);
4459                 set_bit(STRIPE_REPLACED, &sh->state);
4460         }
4461         if ((s.syncing || s.replacing) && s.locked == 0 &&
4462             !test_bit(STRIPE_COMPUTE_RUN, &sh->state) &&
4463             test_bit(STRIPE_INSYNC, &sh->state)) {
4464                 md_done_sync(conf->mddev, STRIPE_SECTORS, 1);
4465                 clear_bit(STRIPE_SYNCING, &sh->state);
4466                 if (test_and_clear_bit(R5_Overlap, &sh->dev[sh->pd_idx].flags))
4467                         wake_up(&conf->wait_for_overlap);
4468         }
4469
4470         /* If the failed drives are just a ReadError, then we might need
4471          * to progress the repair/check process
4472          */
4473         if (s.failed <= conf->max_degraded && !conf->mddev->ro)
4474                 for (i = 0; i < s.failed; i++) {
4475                         struct r5dev *dev = &sh->dev[s.failed_num[i]];
4476                         if (test_bit(R5_ReadError, &dev->flags)
4477                             && !test_bit(R5_LOCKED, &dev->flags)
4478                             && test_bit(R5_UPTODATE, &dev->flags)
4479                                 ) {
4480                                 if (!test_bit(R5_ReWrite, &dev->flags)) {
4481                                         set_bit(R5_Wantwrite, &dev->flags);
4482                                         set_bit(R5_ReWrite, &dev->flags);
4483                                         set_bit(R5_LOCKED, &dev->flags);
4484                                         s.locked++;
4485                                 } else {
4486                                         /* let's read it back */
4487                                         set_bit(R5_Wantread, &dev->flags);
4488                                         set_bit(R5_LOCKED, &dev->flags);
4489                                         s.locked++;
4490                                 }
4491                         }
4492                 }
4493
4494         /* Finish reconstruct operations initiated by the expansion process */
4495         if (sh->reconstruct_state == reconstruct_state_result) {
4496                 struct stripe_head *sh_src
4497                         = get_active_stripe(conf, sh->sector, 1, 1, 1);
4498                 if (sh_src && test_bit(STRIPE_EXPAND_SOURCE, &sh_src->state)) {
4499                         /* sh cannot be written until sh_src has been read.
4500                          * so arrange for sh to be delayed a little
4501                          */
4502                         set_bit(STRIPE_DELAYED, &sh->state);
4503                         set_bit(STRIPE_HANDLE, &sh->state);
4504                         if (!test_and_set_bit(STRIPE_PREREAD_ACTIVE,
4505                                               &sh_src->state))
4506                                 atomic_inc(&conf->preread_active_stripes);
4507                         release_stripe(sh_src);
4508                         goto finish;
4509                 }
4510                 if (sh_src)
4511                         release_stripe(sh_src);
4512
4513                 sh->reconstruct_state = reconstruct_state_idle;
4514                 clear_bit(STRIPE_EXPANDING, &sh->state);
4515                 for (i = conf->raid_disks; i--; ) {
4516                         set_bit(R5_Wantwrite, &sh->dev[i].flags);
4517                         set_bit(R5_LOCKED, &sh->dev[i].flags);
4518                         s.locked++;
4519                 }
4520         }
4521
4522         if (s.expanded && test_bit(STRIPE_EXPANDING, &sh->state) &&
4523             !sh->reconstruct_state) {
4524                 /* Need to write out all blocks after computing parity */
4525                 sh->disks = conf->raid_disks;
4526                 stripe_set_idx(sh->sector, conf, 0, sh);
4527                 schedule_reconstruction(sh, &s, 1, 1);
4528         } else if (s.expanded && !sh->reconstruct_state && s.locked == 0) {
4529                 clear_bit(STRIPE_EXPAND_READY, &sh->state);
4530                 atomic_dec(&conf->reshape_stripes);
4531                 wake_up(&conf->wait_for_overlap);
4532                 md_done_sync(conf->mddev, STRIPE_SECTORS, 1);
4533         }
4534
4535         if (s.expanding && s.locked == 0 &&
4536             !test_bit(STRIPE_COMPUTE_RUN, &sh->state))
4537                 handle_stripe_expansion(conf, sh);
4538
4539 finish:
4540         /* wait for this device to become unblocked */
4541         if (unlikely(s.blocked_rdev)) {
4542                 if (conf->mddev->external)
4543                         md_wait_for_blocked_rdev(s.blocked_rdev,
4544                                                  conf->mddev);
4545                 else
4546                         /* Internal metadata will immediately
4547                          * be written by raid5d, so we don't
4548                          * need to wait here.
4549                          */
4550                         rdev_dec_pending(s.blocked_rdev,
4551                                          conf->mddev);
4552         }
4553
4554         if (s.handle_bad_blocks)
4555                 for (i = disks; i--; ) {
4556                         struct md_rdev *rdev;
4557                         struct r5dev *dev = &sh->dev[i];
4558                         if (test_and_clear_bit(R5_WriteError, &dev->flags)) {
4559                                 /* We own a safe reference to the rdev */
4560                                 rdev = conf->disks[i].rdev;
4561                                 if (!rdev_set_badblocks(rdev, sh->sector,
4562                                                         STRIPE_SECTORS, 0))
4563                                         md_error(conf->mddev, rdev);
4564                                 rdev_dec_pending(rdev, conf->mddev);
4565                         }
4566                         if (test_and_clear_bit(R5_MadeGood, &dev->flags)) {
4567                                 rdev = conf->disks[i].rdev;
4568                                 rdev_clear_badblocks(rdev, sh->sector,
4569                                                      STRIPE_SECTORS, 0);
4570                                 rdev_dec_pending(rdev, conf->mddev);
4571                         }
4572                         if (test_and_clear_bit(R5_MadeGoodRepl, &dev->flags)) {
4573                                 rdev = conf->disks[i].replacement;
4574                                 if (!rdev)
4575                                         /* rdev have been moved down */
4576                                         rdev = conf->disks[i].rdev;
4577                                 rdev_clear_badblocks(rdev, sh->sector,
4578                                                      STRIPE_SECTORS, 0);
4579                                 rdev_dec_pending(rdev, conf->mddev);
4580                         }
4581                 }
4582
4583         if (s.ops_request)
4584                 raid_run_ops(sh, s.ops_request);
4585
4586         ops_run_io(sh, &s);
4587
4588         if (s.dec_preread_active) {
4589                 /* We delay this until after ops_run_io so that if make_request
4590                  * is waiting on a flush, it won't continue until the writes
4591                  * have actually been submitted.
4592                  */
4593                 atomic_dec(&conf->preread_active_stripes);
4594                 if (atomic_read(&conf->preread_active_stripes) <
4595                     IO_THRESHOLD)
4596                         md_wakeup_thread(conf->mddev->thread);
4597         }
4598
4599         return_io(s.return_bi);
4600
4601         clear_bit_unlock(STRIPE_ACTIVE, &sh->state);
4602 }
4603
4604 static void raid5_activate_delayed(struct r5conf *conf)
4605 {
4606         if (atomic_read(&conf->preread_active_stripes) < IO_THRESHOLD) {
4607                 while (!list_empty(&conf->delayed_list)) {
4608                         struct list_head *l = conf->delayed_list.next;
4609                         struct stripe_head *sh;
4610                         sh = list_entry(l, struct stripe_head, lru);
4611                         list_del_init(l);
4612                         clear_bit(STRIPE_DELAYED, &sh->state);
4613                         if (!test_and_set_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
4614                                 atomic_inc(&conf->preread_active_stripes);
4615                         list_add_tail(&sh->lru, &conf->hold_list);
4616                         raid5_wakeup_stripe_thread(sh);
4617                 }
4618         }
4619 }
4620
4621 static void activate_bit_delay(struct r5conf *conf,
4622         struct list_head *temp_inactive_list)
4623 {
4624         /* device_lock is held */
4625         struct list_head head;
4626         list_add(&head, &conf->bitmap_list);
4627         list_del_init(&conf->bitmap_list);
4628         while (!list_empty(&head)) {
4629                 struct stripe_head *sh = list_entry(head.next, struct stripe_head, lru);
4630                 int hash;
4631                 list_del_init(&sh->lru);
4632                 atomic_inc(&sh->count);
4633                 hash = sh->hash_lock_index;
4634                 __release_stripe(conf, sh, &temp_inactive_list[hash]);
4635         }
4636 }
4637
4638 static int raid5_congested(struct mddev *mddev, int bits)
4639 {
4640         struct r5conf *conf = mddev->private;
4641
4642         /* No difference between reads and writes.  Just check
4643          * how busy the stripe_cache is
4644          */
4645
4646         if (test_bit(R5_INACTIVE_BLOCKED, &conf->cache_state))
4647                 return 1;
4648         if (conf->quiesce)
4649                 return 1;
4650         if (atomic_read(&conf->empty_inactive_list_nr))
4651                 return 1;
4652
4653         return 0;
4654 }
4655
4656 /* We want read requests to align with chunks where possible,
4657  * but write requests don't need to.
4658  */
4659 static int raid5_mergeable_bvec(struct mddev *mddev,
4660                                 struct bvec_merge_data *bvm,
4661                                 struct bio_vec *biovec)
4662 {
4663         sector_t sector = bvm->bi_sector + get_start_sect(bvm->bi_bdev);
4664         int max;
4665         unsigned int chunk_sectors = mddev->chunk_sectors;
4666         unsigned int bio_sectors = bvm->bi_size >> 9;
4667
4668         /*
4669          * always allow writes to be mergeable, read as well if array
4670          * is degraded as we'll go through stripe cache anyway.
4671          */
4672         if ((bvm->bi_rw & 1) == WRITE || mddev->degraded)
4673                 return biovec->bv_len;
4674
4675         if (mddev->new_chunk_sectors < mddev->chunk_sectors)
4676                 chunk_sectors = mddev->new_chunk_sectors;
4677         max =  (chunk_sectors - ((sector & (chunk_sectors - 1)) + bio_sectors)) << 9;
4678         if (max < 0) max = 0;
4679         if (max <= biovec->bv_len && bio_sectors == 0)
4680                 return biovec->bv_len;
4681         else
4682                 return max;
4683 }
4684
4685 static int in_chunk_boundary(struct mddev *mddev, struct bio *bio)
4686 {
4687         sector_t sector = bio->bi_iter.bi_sector + get_start_sect(bio->bi_bdev);
4688         unsigned int chunk_sectors = mddev->chunk_sectors;
4689         unsigned int bio_sectors = bio_sectors(bio);
4690
4691         if (mddev->new_chunk_sectors < mddev->chunk_sectors)
4692                 chunk_sectors = mddev->new_chunk_sectors;
4693         return  chunk_sectors >=
4694                 ((sector & (chunk_sectors - 1)) + bio_sectors);
4695 }
4696
4697 /*
4698  *  add bio to the retry LIFO  ( in O(1) ... we are in interrupt )
4699  *  later sampled by raid5d.
4700  */
4701 static void add_bio_to_retry(struct bio *bi,struct r5conf *conf)
4702 {
4703         unsigned long flags;
4704
4705         spin_lock_irqsave(&conf->device_lock, flags);
4706
4707         bi->bi_next = conf->retry_read_aligned_list;
4708         conf->retry_read_aligned_list = bi;
4709
4710         spin_unlock_irqrestore(&conf->device_lock, flags);
4711         md_wakeup_thread(conf->mddev->thread);
4712 }
4713
4714 static struct bio *remove_bio_from_retry(struct r5conf *conf)
4715 {
4716         struct bio *bi;
4717
4718         bi = conf->retry_read_aligned;
4719         if (bi) {
4720                 conf->retry_read_aligned = NULL;
4721                 return bi;
4722         }
4723         bi = conf->retry_read_aligned_list;
4724         if(bi) {
4725                 conf->retry_read_aligned_list = bi->bi_next;
4726                 bi->bi_next = NULL;
4727                 /*
4728                  * this sets the active strip count to 1 and the processed
4729                  * strip count to zero (upper 8 bits)
4730                  */
4731                 raid5_set_bi_stripes(bi, 1); /* biased count of active stripes */
4732         }
4733
4734         return bi;
4735 }
4736
4737 /*
4738  *  The "raid5_align_endio" should check if the read succeeded and if it
4739  *  did, call bio_endio on the original bio (having bio_put the new bio
4740  *  first).
4741  *  If the read failed..
4742  */
4743 static void raid5_align_endio(struct bio *bi, int error)
4744 {
4745         struct bio* raid_bi  = bi->bi_private;
4746         struct mddev *mddev;
4747         struct r5conf *conf;
4748         int uptodate = test_bit(BIO_UPTODATE, &bi->bi_flags);
4749         struct md_rdev *rdev;
4750
4751         bio_put(bi);
4752
4753         rdev = (void*)raid_bi->bi_next;
4754         raid_bi->bi_next = NULL;
4755         mddev = rdev->mddev;
4756         conf = mddev->private;
4757
4758         rdev_dec_pending(rdev, conf->mddev);
4759
4760         if (!error && uptodate) {
4761                 trace_block_bio_complete(bdev_get_queue(raid_bi->bi_bdev),
4762                                          raid_bi, 0);
4763                 bio_endio(raid_bi, 0);
4764                 if (atomic_dec_and_test(&conf->active_aligned_reads))
4765                         wake_up(&conf->wait_for_stripe);
4766                 return;
4767         }
4768
4769         pr_debug("raid5_align_endio : io error...handing IO for a retry\n");
4770
4771         add_bio_to_retry(raid_bi, conf);
4772 }
4773
4774 static int bio_fits_rdev(struct bio *bi)
4775 {
4776         struct request_queue *q = bdev_get_queue(bi->bi_bdev);
4777
4778         if (bio_sectors(bi) > queue_max_sectors(q))
4779                 return 0;
4780         blk_recount_segments(q, bi);
4781         if (bi->bi_phys_segments > queue_max_segments(q))
4782                 return 0;
4783
4784         if (q->merge_bvec_fn)
4785                 /* it's too hard to apply the merge_bvec_fn at this stage,
4786                  * just just give up
4787                  */
4788                 return 0;
4789
4790         return 1;
4791 }
4792
4793 static int chunk_aligned_read(struct mddev *mddev, struct bio * raid_bio)
4794 {
4795         struct r5conf *conf = mddev->private;
4796         int dd_idx;
4797         struct bio* align_bi;
4798         struct md_rdev *rdev;
4799         sector_t end_sector;
4800
4801         if (!in_chunk_boundary(mddev, raid_bio)) {
4802                 pr_debug("chunk_aligned_read : non aligned\n");
4803                 return 0;
4804         }
4805         /*
4806          * use bio_clone_mddev to make a copy of the bio
4807          */
4808         align_bi = bio_clone_mddev(raid_bio, GFP_NOIO, mddev);
4809         if (!align_bi)
4810                 return 0;
4811         /*
4812          *   set bi_end_io to a new function, and set bi_private to the
4813          *     original bio.
4814          */
4815         align_bi->bi_end_io  = raid5_align_endio;
4816         align_bi->bi_private = raid_bio;
4817         /*
4818          *      compute position
4819          */
4820         align_bi->bi_iter.bi_sector =
4821                 raid5_compute_sector(conf, raid_bio->bi_iter.bi_sector,
4822                                      0, &dd_idx, NULL);
4823
4824         end_sector = bio_end_sector(align_bi);
4825         rcu_read_lock();
4826         rdev = rcu_dereference(conf->disks[dd_idx].replacement);
4827         if (!rdev || test_bit(Faulty, &rdev->flags) ||
4828             rdev->recovery_offset < end_sector) {
4829                 rdev = rcu_dereference(conf->disks[dd_idx].rdev);
4830                 if (rdev &&
4831                     (test_bit(Faulty, &rdev->flags) ||
4832                     !(test_bit(In_sync, &rdev->flags) ||
4833                       rdev->recovery_offset >= end_sector)))
4834                         rdev = NULL;
4835         }
4836         if (rdev) {
4837                 sector_t first_bad;
4838                 int bad_sectors;
4839
4840                 atomic_inc(&rdev->nr_pending);
4841                 rcu_read_unlock();
4842                 raid_bio->bi_next = (void*)rdev;
4843                 align_bi->bi_bdev =  rdev->bdev;
4844                 __clear_bit(BIO_SEG_VALID, &align_bi->bi_flags);
4845
4846                 if (!bio_fits_rdev(align_bi) ||
4847                     is_badblock(rdev, align_bi->bi_iter.bi_sector,
4848                                 bio_sectors(align_bi),
4849                                 &first_bad, &bad_sectors)) {
4850                         /* too big in some way, or has a known bad block */
4851                         bio_put(align_bi);
4852                         rdev_dec_pending(rdev, mddev);
4853                         return 0;
4854                 }
4855
4856                 /* No reshape active, so we can trust rdev->data_offset */
4857                 align_bi->bi_iter.bi_sector += rdev->data_offset;
4858
4859                 spin_lock_irq(&conf->device_lock);
4860                 wait_event_lock_irq(conf->wait_for_stripe,
4861                                     conf->quiesce == 0,
4862                                     conf->device_lock);
4863                 atomic_inc(&conf->active_aligned_reads);
4864                 spin_unlock_irq(&conf->device_lock);
4865
4866                 if (mddev->gendisk)
4867                         trace_block_bio_remap(bdev_get_queue(align_bi->bi_bdev),
4868                                               align_bi, disk_devt(mddev->gendisk),
4869                                               raid_bio->bi_iter.bi_sector);
4870                 generic_make_request(align_bi);
4871                 return 1;
4872         } else {
4873                 rcu_read_unlock();
4874                 bio_put(align_bi);
4875                 return 0;
4876         }
4877 }
4878
4879 /* __get_priority_stripe - get the next stripe to process
4880  *
4881  * Full stripe writes are allowed to pass preread active stripes up until
4882  * the bypass_threshold is exceeded.  In general the bypass_count
4883  * increments when the handle_list is handled before the hold_list; however, it
4884  * will not be incremented when STRIPE_IO_STARTED is sampled set signifying a
4885  * stripe with in flight i/o.  The bypass_count will be reset when the
4886  * head of the hold_list has changed, i.e. the head was promoted to the
4887  * handle_list.
4888  */
4889 static struct stripe_head *__get_priority_stripe(struct r5conf *conf, int group)
4890 {
4891         struct stripe_head *sh = NULL, *tmp;
4892         struct list_head *handle_list = NULL;
4893         struct r5worker_group *wg = NULL;
4894
4895         if (conf->worker_cnt_per_group == 0) {
4896                 handle_list = &conf->handle_list;
4897         } else if (group != ANY_GROUP) {
4898                 handle_list = &conf->worker_groups[group].handle_list;
4899                 wg = &conf->worker_groups[group];
4900         } else {
4901                 int i;
4902                 for (i = 0; i < conf->group_cnt; i++) {
4903                         handle_list = &conf->worker_groups[i].handle_list;
4904                         wg = &conf->worker_groups[i];
4905                         if (!list_empty(handle_list))
4906                                 break;
4907                 }
4908         }
4909
4910         pr_debug("%s: handle: %s hold: %s full_writes: %d bypass_count: %d\n",
4911                   __func__,
4912                   list_empty(handle_list) ? "empty" : "busy",
4913                   list_empty(&conf->hold_list) ? "empty" : "busy",
4914                   atomic_read(&conf->pending_full_writes), conf->bypass_count);
4915
4916         if (!list_empty(handle_list)) {
4917                 sh = list_entry(handle_list->next, typeof(*sh), lru);
4918
4919                 if (list_empty(&conf->hold_list))
4920                         conf->bypass_count = 0;
4921                 else if (!test_bit(STRIPE_IO_STARTED, &sh->state)) {
4922                         if (conf->hold_list.next == conf->last_hold)
4923                                 conf->bypass_count++;
4924                         else {
4925                                 conf->last_hold = conf->hold_list.next;
4926                                 conf->bypass_count -= conf->bypass_threshold;
4927                                 if (conf->bypass_count < 0)
4928                                         conf->bypass_count = 0;
4929                         }
4930                 }
4931         } else if (!list_empty(&conf->hold_list) &&
4932                    ((conf->bypass_threshold &&
4933                      conf->bypass_count > conf->bypass_threshold) ||
4934                     atomic_read(&conf->pending_full_writes) == 0)) {
4935
4936                 list_for_each_entry(tmp, &conf->hold_list,  lru) {
4937                         if (conf->worker_cnt_per_group == 0 ||
4938                             group == ANY_GROUP ||
4939                             !cpu_online(tmp->cpu) ||
4940                             cpu_to_group(tmp->cpu) == group) {
4941                                 sh = tmp;
4942                                 break;
4943                         }
4944                 }
4945
4946                 if (sh) {
4947                         conf->bypass_count -= conf->bypass_threshold;
4948                         if (conf->bypass_count < 0)
4949                                 conf->bypass_count = 0;
4950                 }
4951                 wg = NULL;
4952         }
4953
4954         if (!sh)
4955                 return NULL;
4956
4957         if (wg) {
4958                 wg->stripes_cnt--;
4959                 sh->group = NULL;
4960         }
4961         list_del_init(&sh->lru);
4962         BUG_ON(atomic_inc_return(&sh->count) != 1);
4963         return sh;
4964 }
4965
4966 struct raid5_plug_cb {
4967         struct blk_plug_cb      cb;
4968         struct list_head        list;
4969         struct list_head        temp_inactive_list[NR_STRIPE_HASH_LOCKS];
4970 };
4971
4972 static void raid5_unplug(struct blk_plug_cb *blk_cb, bool from_schedule)
4973 {
4974         struct raid5_plug_cb *cb = container_of(
4975                 blk_cb, struct raid5_plug_cb, cb);
4976         struct stripe_head *sh;
4977         struct mddev *mddev = cb->cb.data;
4978         struct r5conf *conf = mddev->private;
4979         int cnt = 0;
4980         int hash;
4981
4982         if (cb->list.next && !list_empty(&cb->list)) {
4983                 spin_lock_irq(&conf->device_lock);
4984                 while (!list_empty(&cb->list)) {
4985                         sh = list_first_entry(&cb->list, struct stripe_head, lru);
4986                         list_del_init(&sh->lru);
4987                         /*
4988                          * avoid race release_stripe_plug() sees
4989                          * STRIPE_ON_UNPLUG_LIST clear but the stripe
4990                          * is still in our list
4991                          */
4992                         smp_mb__before_atomic();
4993                         clear_bit(STRIPE_ON_UNPLUG_LIST, &sh->state);
4994                         /*
4995                          * STRIPE_ON_RELEASE_LIST could be set here. In that
4996                          * case, the count is always > 1 here
4997                          */
4998                         hash = sh->hash_lock_index;
4999                         __release_stripe(conf, sh, &cb->temp_inactive_list[hash]);
5000                         cnt++;
5001                 }
5002                 spin_unlock_irq(&conf->device_lock);
5003         }
5004         release_inactive_stripe_list(conf, cb->temp_inactive_list,
5005                                      NR_STRIPE_HASH_LOCKS);
5006         if (mddev->queue)
5007                 trace_block_unplug(mddev->queue, cnt, !from_schedule);
5008         kfree(cb);
5009 }
5010
5011 static void release_stripe_plug(struct mddev *mddev,
5012                                 struct stripe_head *sh)
5013 {
5014         struct blk_plug_cb *blk_cb = blk_check_plugged(
5015                 raid5_unplug, mddev,
5016                 sizeof(struct raid5_plug_cb));
5017         struct raid5_plug_cb *cb;
5018
5019         if (!blk_cb) {
5020                 release_stripe(sh);
5021                 return;
5022         }
5023
5024         cb = container_of(blk_cb, struct raid5_plug_cb, cb);
5025
5026         if (cb->list.next == NULL) {
5027                 int i;
5028                 INIT_LIST_HEAD(&cb->list);
5029                 for (i = 0; i < NR_STRIPE_HASH_LOCKS; i++)
5030                         INIT_LIST_HEAD(cb->temp_inactive_list + i);
5031         }
5032
5033         if (!test_and_set_bit(STRIPE_ON_UNPLUG_LIST, &sh->state))
5034                 list_add_tail(&sh->lru, &cb->list);
5035         else
5036                 release_stripe(sh);
5037 }
5038
5039 static void make_discard_request(struct mddev *mddev, struct bio *bi)
5040 {
5041         struct r5conf *conf = mddev->private;
5042         sector_t logical_sector, last_sector;
5043         struct stripe_head *sh;
5044         int remaining;
5045         int stripe_sectors;
5046
5047         if (mddev->reshape_position != MaxSector)
5048                 /* Skip discard while reshape is happening */
5049                 return;
5050
5051         logical_sector = bi->bi_iter.bi_sector & ~((sector_t)STRIPE_SECTORS-1);
5052         last_sector = bi->bi_iter.bi_sector + (bi->bi_iter.bi_size>>9);
5053
5054         bi->bi_next = NULL;
5055         bi->bi_phys_segments = 1; /* over-loaded to count active stripes */
5056
5057         stripe_sectors = conf->chunk_sectors *
5058                 (conf->raid_disks - conf->max_degraded);
5059         logical_sector = DIV_ROUND_UP_SECTOR_T(logical_sector,
5060                                                stripe_sectors);
5061         sector_div(last_sector, stripe_sectors);
5062
5063         logical_sector *= conf->chunk_sectors;
5064         last_sector *= conf->chunk_sectors;
5065
5066         for (; logical_sector < last_sector;
5067              logical_sector += STRIPE_SECTORS) {
5068                 DEFINE_WAIT(w);
5069                 int d;
5070         again:
5071                 sh = get_active_stripe(conf, logical_sector, 0, 0, 0);
5072                 prepare_to_wait(&conf->wait_for_overlap, &w,
5073                                 TASK_UNINTERRUPTIBLE);
5074                 set_bit(R5_Overlap, &sh->dev[sh->pd_idx].flags);
5075                 if (test_bit(STRIPE_SYNCING, &sh->state)) {
5076                         release_stripe(sh);
5077                         schedule();
5078                         goto again;
5079                 }
5080                 clear_bit(R5_Overlap, &sh->dev[sh->pd_idx].flags);
5081                 spin_lock_irq(&sh->stripe_lock);
5082                 for (d = 0; d < conf->raid_disks; d++) {
5083                         if (d == sh->pd_idx || d == sh->qd_idx)
5084                                 continue;
5085                         if (sh->dev[d].towrite || sh->dev[d].toread) {
5086                                 set_bit(R5_Overlap, &sh->dev[d].flags);
5087                                 spin_unlock_irq(&sh->stripe_lock);
5088                                 release_stripe(sh);
5089                                 schedule();
5090                                 goto again;
5091                         }
5092                 }
5093                 set_bit(STRIPE_DISCARD, &sh->state);
5094                 finish_wait(&conf->wait_for_overlap, &w);
5095                 sh->overwrite_disks = 0;
5096                 for (d = 0; d < conf->raid_disks; d++) {
5097                         if (d == sh->pd_idx || d == sh->qd_idx)
5098                                 continue;
5099                         sh->dev[d].towrite = bi;
5100                         set_bit(R5_OVERWRITE, &sh->dev[d].flags);
5101                         raid5_inc_bi_active_stripes(bi);
5102                         sh->overwrite_disks++;
5103                 }
5104                 spin_unlock_irq(&sh->stripe_lock);
5105                 if (conf->mddev->bitmap) {
5106                         for (d = 0;
5107                              d < conf->raid_disks - conf->max_degraded;
5108                              d++)
5109                                 bitmap_startwrite(mddev->bitmap,
5110                                                   sh->sector,
5111                                                   STRIPE_SECTORS,
5112                                                   0);
5113                         sh->bm_seq = conf->seq_flush + 1;
5114                         set_bit(STRIPE_BIT_DELAY, &sh->state);
5115                 }
5116
5117                 set_bit(STRIPE_HANDLE, &sh->state);
5118                 clear_bit(STRIPE_DELAYED, &sh->state);
5119                 if (!test_and_set_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
5120                         atomic_inc(&conf->preread_active_stripes);
5121                 release_stripe_plug(mddev, sh);
5122         }
5123
5124         remaining = raid5_dec_bi_active_stripes(bi);
5125         if (remaining == 0) {
5126                 md_write_end(mddev);
5127                 bio_endio(bi, 0);
5128         }
5129 }
5130
5131 static void make_request(struct mddev *mddev, struct bio * bi)
5132 {
5133         struct r5conf *conf = mddev->private;
5134         int dd_idx;
5135         sector_t new_sector;
5136         sector_t logical_sector, last_sector;
5137         struct stripe_head *sh;
5138         const int rw = bio_data_dir(bi);
5139         int remaining;
5140         DEFINE_WAIT(w);
5141         bool do_prepare;
5142
5143         if (unlikely(bi->bi_rw & REQ_FLUSH)) {
5144                 md_flush_request(mddev, bi);
5145                 return;
5146         }
5147
5148         md_write_start(mddev, bi);
5149
5150         /*
5151          * If array is degraded, better not do chunk aligned read because
5152          * later we might have to read it again in order to reconstruct
5153          * data on failed drives.
5154          */
5155         if (rw == READ && mddev->degraded == 0 &&
5156              mddev->reshape_position == MaxSector &&
5157              chunk_aligned_read(mddev,bi))
5158                 return;
5159
5160         if (unlikely(bi->bi_rw & REQ_DISCARD)) {
5161                 make_discard_request(mddev, bi);
5162                 return;
5163         }
5164
5165         logical_sector = bi->bi_iter.bi_sector & ~((sector_t)STRIPE_SECTORS-1);
5166         last_sector = bio_end_sector(bi);
5167         bi->bi_next = NULL;
5168         bi->bi_phys_segments = 1;       /* over-loaded to count active stripes */
5169
5170         prepare_to_wait(&conf->wait_for_overlap, &w, TASK_UNINTERRUPTIBLE);
5171         for (;logical_sector < last_sector; logical_sector += STRIPE_SECTORS) {
5172                 int previous;
5173                 int seq;
5174
5175                 do_prepare = false;
5176         retry:
5177                 seq = read_seqcount_begin(&conf->gen_lock);
5178                 previous = 0;
5179                 if (do_prepare)
5180                         prepare_to_wait(&conf->wait_for_overlap, &w,
5181                                 TASK_UNINTERRUPTIBLE);
5182                 if (unlikely(conf->reshape_progress != MaxSector)) {
5183                         /* spinlock is needed as reshape_progress may be
5184                          * 64bit on a 32bit platform, and so it might be
5185                          * possible to see a half-updated value
5186                          * Of course reshape_progress could change after
5187                          * the lock is dropped, so once we get a reference
5188                          * to the stripe that we think it is, we will have
5189                          * to check again.
5190                          */
5191                         spin_lock_irq(&conf->device_lock);
5192                         if (mddev->reshape_backwards
5193                             ? logical_sector < conf->reshape_progress
5194                             : logical_sector >= conf->reshape_progress) {
5195                                 previous = 1;
5196                         } else {
5197                                 if (mddev->reshape_backwards
5198                                     ? logical_sector < conf->reshape_safe
5199                                     : logical_sector >= conf->reshape_safe) {
5200                                         spin_unlock_irq(&conf->device_lock);
5201                                         schedule();
5202                                         do_prepare = true;
5203                                         goto retry;
5204                                 }
5205                         }
5206                         spin_unlock_irq(&conf->device_lock);
5207                 }
5208
5209                 new_sector = raid5_compute_sector(conf, logical_sector,
5210                                                   previous,
5211                                                   &dd_idx, NULL);
5212                 pr_debug("raid456: make_request, sector %llu logical %llu\n",
5213                         (unsigned long long)new_sector,
5214                         (unsigned long long)logical_sector);
5215
5216                 sh = get_active_stripe(conf, new_sector, previous,
5217                                        (bi->bi_rw&RWA_MASK), 0);
5218                 if (sh) {
5219                         if (unlikely(previous)) {
5220                                 /* expansion might have moved on while waiting for a
5221                                  * stripe, so we must do the range check again.
5222                                  * Expansion could still move past after this
5223                                  * test, but as we are holding a reference to
5224                                  * 'sh', we know that if that happens,
5225                                  *  STRIPE_EXPANDING will get set and the expansion
5226                                  * won't proceed until we finish with the stripe.
5227                                  */
5228                                 int must_retry = 0;
5229                                 spin_lock_irq(&conf->device_lock);
5230                                 if (mddev->reshape_backwards
5231                                     ? logical_sector >= conf->reshape_progress
5232                                     : logical_sector < conf->reshape_progress)
5233                                         /* mismatch, need to try again */
5234                                         must_retry = 1;
5235                                 spin_unlock_irq(&conf->device_lock);
5236                                 if (must_retry) {
5237                                         release_stripe(sh);
5238                                         schedule();
5239                                         do_prepare = true;
5240                                         goto retry;
5241                                 }
5242                         }
5243                         if (read_seqcount_retry(&conf->gen_lock, seq)) {
5244                                 /* Might have got the wrong stripe_head
5245                                  * by accident
5246                                  */
5247                                 release_stripe(sh);
5248                                 goto retry;
5249                         }
5250
5251                         if (rw == WRITE &&
5252                             logical_sector >= mddev->suspend_lo &&
5253                             logical_sector < mddev->suspend_hi) {
5254                                 release_stripe(sh);
5255                                 /* As the suspend_* range is controlled by
5256                                  * userspace, we want an interruptible
5257                                  * wait.
5258                                  */
5259                                 flush_signals(current);
5260                                 prepare_to_wait(&conf->wait_for_overlap,
5261                                                 &w, TASK_INTERRUPTIBLE);
5262                                 if (logical_sector >= mddev->suspend_lo &&
5263                                     logical_sector < mddev->suspend_hi) {
5264                                         schedule();
5265                                         do_prepare = true;
5266                                 }
5267                                 goto retry;
5268                         }
5269
5270                         if (test_bit(STRIPE_EXPANDING, &sh->state) ||
5271                             !add_stripe_bio(sh, bi, dd_idx, rw, previous)) {
5272                                 /* Stripe is busy expanding or
5273                                  * add failed due to overlap.  Flush everything
5274                                  * and wait a while
5275                                  */
5276                                 md_wakeup_thread(mddev->thread);
5277                                 release_stripe(sh);
5278                                 schedule();
5279                                 do_prepare = true;
5280                                 goto retry;
5281                         }
5282                         set_bit(STRIPE_HANDLE, &sh->state);
5283                         clear_bit(STRIPE_DELAYED, &sh->state);
5284                         if ((!sh->batch_head || sh == sh->batch_head) &&
5285                             (bi->bi_rw & REQ_SYNC) &&
5286                             !test_and_set_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
5287                                 atomic_inc(&conf->preread_active_stripes);
5288                         release_stripe_plug(mddev, sh);
5289                 } else {
5290                         /* cannot get stripe for read-ahead, just give-up */
5291                         clear_bit(BIO_UPTODATE, &bi->bi_flags);
5292                         break;
5293                 }
5294         }
5295         finish_wait(&conf->wait_for_overlap, &w);
5296
5297         remaining = raid5_dec_bi_active_stripes(bi);
5298         if (remaining == 0) {
5299
5300                 if ( rw == WRITE )
5301                         md_write_end(mddev);
5302
5303                 trace_block_bio_complete(bdev_get_queue(bi->bi_bdev),
5304                                          bi, 0);
5305                 bio_endio(bi, 0);
5306         }
5307 }
5308
5309 static sector_t raid5_size(struct mddev *mddev, sector_t sectors, int raid_disks);
5310
5311 static sector_t reshape_request(struct mddev *mddev, sector_t sector_nr, int *skipped)
5312 {
5313         /* reshaping is quite different to recovery/resync so it is
5314          * handled quite separately ... here.
5315          *
5316          * On each call to sync_request, we gather one chunk worth of
5317          * destination stripes and flag them as expanding.
5318          * Then we find all the source stripes and request reads.
5319          * As the reads complete, handle_stripe will copy the data
5320          * into the destination stripe and release that stripe.
5321          */
5322         struct r5conf *conf = mddev->private;
5323         struct stripe_head *sh;
5324         sector_t first_sector, last_sector;
5325         int raid_disks = conf->previous_raid_disks;
5326         int data_disks = raid_disks - conf->max_degraded;
5327         int new_data_disks = conf->raid_disks - conf->max_degraded;
5328         int i;
5329         int dd_idx;
5330         sector_t writepos, readpos, safepos;
5331         sector_t stripe_addr;
5332         int reshape_sectors;
5333         struct list_head stripes;
5334
5335         if (sector_nr == 0) {
5336                 /* If restarting in the middle, skip the initial sectors */
5337                 if (mddev->reshape_backwards &&
5338                     conf->reshape_progress < raid5_size(mddev, 0, 0)) {
5339                         sector_nr = raid5_size(mddev, 0, 0)
5340                                 - conf->reshape_progress;
5341                 } else if (!mddev->reshape_backwards &&
5342                            conf->reshape_progress > 0)
5343                         sector_nr = conf->reshape_progress;
5344                 sector_div(sector_nr, new_data_disks);
5345                 if (sector_nr) {
5346                         mddev->curr_resync_completed = sector_nr;
5347                         sysfs_notify(&mddev->kobj, NULL, "sync_completed");
5348                         *skipped = 1;
5349                         return sector_nr;
5350                 }
5351         }
5352
5353         /* We need to process a full chunk at a time.
5354          * If old and new chunk sizes differ, we need to process the
5355          * largest of these
5356          */
5357         if (mddev->new_chunk_sectors > mddev->chunk_sectors)
5358                 reshape_sectors = mddev->new_chunk_sectors;
5359         else
5360                 reshape_sectors = mddev->chunk_sectors;
5361
5362         /* We update the metadata at least every 10 seconds, or when
5363          * the data about to be copied would over-write the source of
5364          * the data at the front of the range.  i.e. one new_stripe
5365          * along from reshape_progress new_maps to after where
5366          * reshape_safe old_maps to
5367          */
5368         writepos = conf->reshape_progress;
5369         sector_div(writepos, new_data_disks);
5370         readpos = conf->reshape_progress;
5371         sector_div(readpos, data_disks);
5372         safepos = conf->reshape_safe;
5373         sector_div(safepos, data_disks);
5374         if (mddev->reshape_backwards) {
5375                 writepos -= min_t(sector_t, reshape_sectors, writepos);
5376                 readpos += reshape_sectors;
5377                 safepos += reshape_sectors;
5378         } else {
5379                 writepos += reshape_sectors;
5380                 readpos -= min_t(sector_t, reshape_sectors, readpos);
5381                 safepos -= min_t(sector_t, reshape_sectors, safepos);
5382         }
5383
5384         /* Having calculated the 'writepos' possibly use it
5385          * to set 'stripe_addr' which is where we will write to.
5386          */
5387         if (mddev->reshape_backwards) {
5388                 BUG_ON(conf->reshape_progress == 0);
5389                 stripe_addr = writepos;
5390                 BUG_ON((mddev->dev_sectors &
5391                         ~((sector_t)reshape_sectors - 1))
5392                        - reshape_sectors - stripe_addr
5393                        != sector_nr);
5394         } else {
5395                 BUG_ON(writepos != sector_nr + reshape_sectors);
5396                 stripe_addr = sector_nr;
5397         }
5398
5399         /* 'writepos' is the most advanced device address we might write.
5400          * 'readpos' is the least advanced device address we might read.
5401          * 'safepos' is the least address recorded in the metadata as having
5402          *     been reshaped.
5403          * If there is a min_offset_diff, these are adjusted either by
5404          * increasing the safepos/readpos if diff is negative, or
5405          * increasing writepos if diff is positive.
5406          * If 'readpos' is then behind 'writepos', there is no way that we can
5407          * ensure safety in the face of a crash - that must be done by userspace
5408          * making a backup of the data.  So in that case there is no particular
5409          * rush to update metadata.
5410          * Otherwise if 'safepos' is behind 'writepos', then we really need to
5411          * update the metadata to advance 'safepos' to match 'readpos' so that
5412          * we can be safe in the event of a crash.
5413          * So we insist on updating metadata if safepos is behind writepos and
5414          * readpos is beyond writepos.
5415          * In any case, update the metadata every 10 seconds.
5416          * Maybe that number should be configurable, but I'm not sure it is
5417          * worth it.... maybe it could be a multiple of safemode_delay???
5418          */
5419         if (conf->min_offset_diff < 0) {
5420                 safepos += -conf->min_offset_diff;
5421                 readpos += -conf->min_offset_diff;
5422         } else
5423                 writepos += conf->min_offset_diff;
5424
5425         if ((mddev->reshape_backwards
5426              ? (safepos > writepos && readpos < writepos)
5427              : (safepos < writepos && readpos > writepos)) ||
5428             time_after(jiffies, conf->reshape_checkpoint + 10*HZ)) {
5429                 /* Cannot proceed until we've updated the superblock... */
5430                 wait_event(conf->wait_for_overlap,
5431                            atomic_read(&conf->reshape_stripes)==0
5432                            || test_bit(MD_RECOVERY_INTR, &mddev->recovery));
5433                 if (atomic_read(&conf->reshape_stripes) != 0)
5434                         return 0;
5435                 mddev->reshape_position = conf->reshape_progress;
5436                 mddev->curr_resync_completed = sector_nr;
5437                 conf->reshape_checkpoint = jiffies;
5438                 set_bit(MD_CHANGE_DEVS, &mddev->flags);
5439                 md_wakeup_thread(mddev->thread);
5440                 wait_event(mddev->sb_wait, mddev->flags == 0 ||
5441                            test_bit(MD_RECOVERY_INTR, &mddev->recovery));
5442                 if (test_bit(MD_RECOVERY_INTR, &mddev->recovery))
5443                         return 0;
5444                 spin_lock_irq(&conf->device_lock);
5445                 conf->reshape_safe = mddev->reshape_position;
5446                 spin_unlock_irq(&conf->device_lock);
5447                 wake_up(&conf->wait_for_overlap);
5448                 sysfs_notify(&mddev->kobj, NULL, "sync_completed");
5449         }
5450
5451         INIT_LIST_HEAD(&stripes);
5452         for (i = 0; i < reshape_sectors; i += STRIPE_SECTORS) {
5453                 int j;
5454                 int skipped_disk = 0;
5455                 sh = get_active_stripe(conf, stripe_addr+i, 0, 0, 1);
5456                 set_bit(STRIPE_EXPANDING, &sh->state);
5457                 atomic_inc(&conf->reshape_stripes);
5458                 /* If any of this stripe is beyond the end of the old
5459                  * array, then we need to zero those blocks
5460                  */
5461                 for (j=sh->disks; j--;) {
5462                         sector_t s;
5463                         if (j == sh->pd_idx)
5464                                 continue;
5465                         if (conf->level == 6 &&
5466                             j == sh->qd_idx)
5467                                 continue;
5468                         s = compute_blocknr(sh, j, 0);
5469                         if (s < raid5_size(mddev, 0, 0)) {
5470                                 skipped_disk = 1;
5471                                 continue;
5472                         }
5473                         memset(page_address(sh->dev[j].page), 0, STRIPE_SIZE);
5474                         set_bit(R5_Expanded, &sh->dev[j].flags);
5475                         set_bit(R5_UPTODATE, &sh->dev[j].flags);
5476                 }
5477                 if (!skipped_disk) {
5478                         set_bit(STRIPE_EXPAND_READY, &sh->state);
5479                         set_bit(STRIPE_HANDLE, &sh->state);
5480                 }
5481                 list_add(&sh->lru, &stripes);
5482         }
5483         spin_lock_irq(&conf->device_lock);
5484         if (mddev->reshape_backwards)
5485                 conf->reshape_progress -= reshape_sectors * new_data_disks;
5486         else
5487                 conf->reshape_progress += reshape_sectors * new_data_disks;
5488         spin_unlock_irq(&conf->device_lock);
5489         /* Ok, those stripe are ready. We can start scheduling
5490          * reads on the source stripes.
5491          * The source stripes are determined by mapping the first and last
5492          * block on the destination stripes.
5493          */
5494         first_sector =
5495                 raid5_compute_sector(conf, stripe_addr*(new_data_disks),
5496                                      1, &dd_idx, NULL);
5497         last_sector =
5498                 raid5_compute_sector(conf, ((stripe_addr+reshape_sectors)
5499                                             * new_data_disks - 1),
5500                                      1, &dd_idx, NULL);
5501         if (last_sector >= mddev->dev_sectors)
5502                 last_sector = mddev->dev_sectors - 1;
5503         while (first_sector <= last_sector) {
5504                 sh = get_active_stripe(conf, first_sector, 1, 0, 1);
5505                 set_bit(STRIPE_EXPAND_SOURCE, &sh->state);
5506                 set_bit(STRIPE_HANDLE, &sh->state);
5507                 release_stripe(sh);
5508                 first_sector += STRIPE_SECTORS;
5509         }
5510         /* Now that the sources are clearly marked, we can release
5511          * the destination stripes
5512          */
5513         while (!list_empty(&stripes)) {
5514                 sh = list_entry(stripes.next, struct stripe_head, lru);
5515                 list_del_init(&sh->lru);
5516                 release_stripe(sh);
5517         }
5518         /* If this takes us to the resync_max point where we have to pause,
5519          * then we need to write out the superblock.
5520          */
5521         sector_nr += reshape_sectors;
5522         if ((sector_nr - mddev->curr_resync_completed) * 2
5523             >= mddev->resync_max - mddev->curr_resync_completed) {
5524                 /* Cannot proceed until we've updated the superblock... */
5525                 wait_event(conf->wait_for_overlap,
5526                            atomic_read(&conf->reshape_stripes) == 0
5527                            || test_bit(MD_RECOVERY_INTR, &mddev->recovery));
5528                 if (atomic_read(&conf->reshape_stripes) != 0)
5529                         goto ret;
5530                 mddev->reshape_position = conf->reshape_progress;
5531                 mddev->curr_resync_completed = sector_nr;
5532                 conf->reshape_checkpoint = jiffies;
5533                 set_bit(MD_CHANGE_DEVS, &mddev->flags);
5534                 md_wakeup_thread(mddev->thread);
5535                 wait_event(mddev->sb_wait,
5536                            !test_bit(MD_CHANGE_DEVS, &mddev->flags)
5537                            || test_bit(MD_RECOVERY_INTR, &mddev->recovery));
5538                 if (test_bit(MD_RECOVERY_INTR, &mddev->recovery))
5539                         goto ret;
5540                 spin_lock_irq(&conf->device_lock);
5541                 conf->reshape_safe = mddev->reshape_position;
5542                 spin_unlock_irq(&conf->device_lock);
5543                 wake_up(&conf->wait_for_overlap);
5544                 sysfs_notify(&mddev->kobj, NULL, "sync_completed");
5545         }
5546 ret:
5547         return reshape_sectors;
5548 }
5549
5550 static inline sector_t sync_request(struct mddev *mddev, sector_t sector_nr, int *skipped)
5551 {
5552         struct r5conf *conf = mddev->private;
5553         struct stripe_head *sh;
5554         sector_t max_sector = mddev->dev_sectors;
5555         sector_t sync_blocks;
5556         int still_degraded = 0;
5557         int i;
5558
5559         if (sector_nr >= max_sector) {
5560                 /* just being told to finish up .. nothing much to do */
5561
5562                 if (test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery)) {
5563                         end_reshape(conf);
5564                         return 0;
5565                 }
5566
5567                 if (mddev->curr_resync < max_sector) /* aborted */
5568                         bitmap_end_sync(mddev->bitmap, mddev->curr_resync,
5569                                         &sync_blocks, 1);
5570                 else /* completed sync */
5571                         conf->fullsync = 0;
5572                 bitmap_close_sync(mddev->bitmap);
5573
5574                 return 0;
5575         }
5576
5577         /* Allow raid5_quiesce to complete */
5578         wait_event(conf->wait_for_overlap, conf->quiesce != 2);
5579
5580         if (test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery))
5581                 return reshape_request(mddev, sector_nr, skipped);
5582
5583         /* No need to check resync_max as we never do more than one
5584          * stripe, and as resync_max will always be on a chunk boundary,
5585          * if the check in md_do_sync didn't fire, there is no chance
5586          * of overstepping resync_max here
5587          */
5588
5589         /* if there is too many failed drives and we are trying
5590          * to resync, then assert that we are finished, because there is
5591          * nothing we can do.
5592          */
5593         if (mddev->degraded >= conf->max_degraded &&
5594             test_bit(MD_RECOVERY_SYNC, &mddev->recovery)) {
5595                 sector_t rv = mddev->dev_sectors - sector_nr;
5596                 *skipped = 1;
5597                 return rv;
5598         }
5599         if (!test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery) &&
5600             !conf->fullsync &&
5601             !bitmap_start_sync(mddev->bitmap, sector_nr, &sync_blocks, 1) &&
5602             sync_blocks >= STRIPE_SECTORS) {
5603                 /* we can skip this block, and probably more */
5604                 sync_blocks /= STRIPE_SECTORS;
5605                 *skipped = 1;
5606                 return sync_blocks * STRIPE_SECTORS; /* keep things rounded to whole stripes */
5607         }
5608
5609         bitmap_cond_end_sync(mddev->bitmap, sector_nr);
5610
5611         sh = get_active_stripe(conf, sector_nr, 0, 1, 0);
5612         if (sh == NULL) {
5613                 sh = get_active_stripe(conf, sector_nr, 0, 0, 0);
5614                 /* make sure we don't swamp the stripe cache if someone else
5615                  * is trying to get access
5616                  */
5617                 schedule_timeout_uninterruptible(1);
5618         }
5619         /* Need to check if array will still be degraded after recovery/resync
5620          * Note in case of > 1 drive failures it's possible we're rebuilding
5621          * one drive while leaving another faulty drive in array.
5622          */
5623         rcu_read_lock();
5624         for (i = 0; i < conf->raid_disks; i++) {
5625                 struct md_rdev *rdev = ACCESS_ONCE(conf->disks[i].rdev);
5626
5627                 if (rdev == NULL || test_bit(Faulty, &rdev->flags))
5628                         still_degraded = 1;
5629         }
5630         rcu_read_unlock();
5631
5632         bitmap_start_sync(mddev->bitmap, sector_nr, &sync_blocks, still_degraded);
5633
5634         set_bit(STRIPE_SYNC_REQUESTED, &sh->state);
5635         set_bit(STRIPE_HANDLE, &sh->state);
5636
5637         release_stripe(sh);
5638
5639         return STRIPE_SECTORS;
5640 }
5641
5642 static int  retry_aligned_read(struct r5conf *conf, struct bio *raid_bio)
5643 {
5644         /* We may not be able to submit a whole bio at once as there
5645          * may not be enough stripe_heads available.
5646          * We cannot pre-allocate enough stripe_heads as we may need
5647          * more than exist in the cache (if we allow ever large chunks).
5648          * So we do one stripe head at a time and record in
5649          * ->bi_hw_segments how many have been done.
5650          *
5651          * We *know* that this entire raid_bio is in one chunk, so
5652          * it will be only one 'dd_idx' and only need one call to raid5_compute_sector.
5653          */
5654         struct stripe_head *sh;
5655         int dd_idx;
5656         sector_t sector, logical_sector, last_sector;
5657         int scnt = 0;
5658         int remaining;
5659         int handled = 0;
5660
5661         logical_sector = raid_bio->bi_iter.bi_sector &
5662                 ~((sector_t)STRIPE_SECTORS-1);
5663         sector = raid5_compute_sector(conf, logical_sector,
5664                                       0, &dd_idx, NULL);
5665         last_sector = bio_end_sector(raid_bio);
5666
5667         for (; logical_sector < last_sector;
5668              logical_sector += STRIPE_SECTORS,
5669                      sector += STRIPE_SECTORS,
5670                      scnt++) {
5671
5672                 if (scnt < raid5_bi_processed_stripes(raid_bio))
5673                         /* already done this stripe */
5674                         continue;
5675
5676                 sh = get_active_stripe(conf, sector, 0, 1, 1);
5677
5678                 if (!sh) {
5679                         /* failed to get a stripe - must wait */
5680                         raid5_set_bi_processed_stripes(raid_bio, scnt);
5681                         conf->retry_read_aligned = raid_bio;
5682                         return handled;
5683                 }
5684
5685                 if (!add_stripe_bio(sh, raid_bio, dd_idx, 0, 0)) {
5686                         release_stripe(sh);
5687                         raid5_set_bi_processed_stripes(raid_bio, scnt);
5688                         conf->retry_read_aligned = raid_bio;
5689                         return handled;
5690                 }
5691
5692                 set_bit(R5_ReadNoMerge, &sh->dev[dd_idx].flags);
5693                 handle_stripe(sh);
5694                 release_stripe(sh);
5695                 handled++;
5696         }
5697         remaining = raid5_dec_bi_active_stripes(raid_bio);
5698         if (remaining == 0) {
5699                 trace_block_bio_complete(bdev_get_queue(raid_bio->bi_bdev),
5700                                          raid_bio, 0);
5701                 bio_endio(raid_bio, 0);
5702         }
5703         if (atomic_dec_and_test(&conf->active_aligned_reads))
5704                 wake_up(&conf->wait_for_stripe);
5705         return handled;
5706 }
5707
5708 static int handle_active_stripes(struct r5conf *conf, int group,
5709                                  struct r5worker *worker,
5710                                  struct list_head *temp_inactive_list)
5711 {
5712         struct stripe_head *batch[MAX_STRIPE_BATCH], *sh;
5713         int i, batch_size = 0, hash;
5714         bool release_inactive = false;
5715
5716         while (batch_size < MAX_STRIPE_BATCH &&
5717                         (sh = __get_priority_stripe(conf, group)) != NULL)
5718                 batch[batch_size++] = sh;
5719
5720         if (batch_size == 0) {
5721                 for (i = 0; i < NR_STRIPE_HASH_LOCKS; i++)
5722                         if (!list_empty(temp_inactive_list + i))
5723                                 break;
5724                 if (i == NR_STRIPE_HASH_LOCKS)
5725                         return batch_size;
5726                 release_inactive = true;
5727         }
5728         spin_unlock_irq(&conf->device_lock);
5729
5730         release_inactive_stripe_list(conf, temp_inactive_list,
5731                                      NR_STRIPE_HASH_LOCKS);
5732
5733         if (release_inactive) {
5734                 spin_lock_irq(&conf->device_lock);
5735                 return 0;
5736         }
5737
5738         for (i = 0; i < batch_size; i++)
5739                 handle_stripe(batch[i]);
5740
5741         cond_resched();
5742
5743         spin_lock_irq(&conf->device_lock);
5744         for (i = 0; i < batch_size; i++) {
5745                 hash = batch[i]->hash_lock_index;
5746                 __release_stripe(conf, batch[i], &temp_inactive_list[hash]);
5747         }
5748         return batch_size;
5749 }
5750
5751 static void raid5_do_work(struct work_struct *work)
5752 {
5753         struct r5worker *worker = container_of(work, struct r5worker, work);
5754         struct r5worker_group *group = worker->group;
5755         struct r5conf *conf = group->conf;
5756         int group_id = group - conf->worker_groups;
5757         int handled;
5758         struct blk_plug plug;
5759
5760         pr_debug("+++ raid5worker active\n");
5761
5762         blk_start_plug(&plug);
5763         handled = 0;
5764         spin_lock_irq(&conf->device_lock);
5765         while (1) {
5766                 int batch_size, released;
5767
5768                 released = release_stripe_list(conf, worker->temp_inactive_list);
5769
5770                 batch_size = handle_active_stripes(conf, group_id, worker,
5771                                                    worker->temp_inactive_list);
5772                 worker->working = false;
5773                 if (!batch_size && !released)
5774                         break;
5775                 handled += batch_size;
5776         }
5777         pr_debug("%d stripes handled\n", handled);
5778
5779         spin_unlock_irq(&conf->device_lock);
5780         blk_finish_plug(&plug);
5781
5782         pr_debug("--- raid5worker inactive\n");
5783 }
5784
5785 /*
5786  * This is our raid5 kernel thread.
5787  *
5788  * We scan the hash table for stripes which can be handled now.
5789  * During the scan, completed stripes are saved for us by the interrupt
5790  * handler, so that they will not have to wait for our next wakeup.
5791  */
5792 static void raid5d(struct md_thread *thread)
5793 {
5794         struct mddev *mddev = thread->mddev;
5795         struct r5conf *conf = mddev->private;
5796         int handled;
5797         struct blk_plug plug;
5798
5799         pr_debug("+++ raid5d active\n");
5800
5801         md_check_recovery(mddev);
5802
5803         blk_start_plug(&plug);
5804         handled = 0;
5805         spin_lock_irq(&conf->device_lock);
5806         while (1) {
5807                 struct bio *bio;
5808                 int batch_size, released;
5809
5810                 released = release_stripe_list(conf, conf->temp_inactive_list);
5811                 if (released)
5812                         clear_bit(R5_DID_ALLOC, &conf->cache_state);
5813
5814                 if (
5815                     !list_empty(&conf->bitmap_list)) {
5816                         /* Now is a good time to flush some bitmap updates */
5817                         conf->seq_flush++;
5818                         spin_unlock_irq(&conf->device_lock);
5819                         bitmap_unplug(mddev->bitmap);
5820                         spin_lock_irq(&conf->device_lock);
5821                         conf->seq_write = conf->seq_flush;
5822                         activate_bit_delay(conf, conf->temp_inactive_list);
5823                 }
5824                 raid5_activate_delayed(conf);
5825
5826                 while ((bio = remove_bio_from_retry(conf))) {
5827                         int ok;
5828                         spin_unlock_irq(&conf->device_lock);
5829                         ok = retry_aligned_read(conf, bio);
5830                         spin_lock_irq(&conf->device_lock);
5831                         if (!ok)
5832                                 break;
5833                         handled++;
5834                 }
5835
5836                 batch_size = handle_active_stripes(conf, ANY_GROUP, NULL,
5837                                                    conf->temp_inactive_list);
5838                 if (!batch_size && !released)
5839                         break;
5840                 handled += batch_size;
5841
5842                 if (mddev->flags & ~(1<<MD_CHANGE_PENDING)) {
5843                         spin_unlock_irq(&conf->device_lock);
5844                         md_check_recovery(mddev);
5845                         spin_lock_irq(&conf->device_lock);
5846                 }
5847         }
5848         pr_debug("%d stripes handled\n", handled);
5849
5850         spin_unlock_irq(&conf->device_lock);
5851         if (test_and_clear_bit(R5_ALLOC_MORE, &conf->cache_state)) {
5852                 grow_one_stripe(conf, __GFP_NOWARN);
5853                 /* Set flag even if allocation failed.  This helps
5854                  * slow down allocation requests when mem is short
5855                  */
5856                 set_bit(R5_DID_ALLOC, &conf->cache_state);
5857         }
5858
5859         async_tx_issue_pending_all();
5860         blk_finish_plug(&plug);
5861
5862         pr_debug("--- raid5d inactive\n");
5863 }
5864
5865 static ssize_t
5866 raid5_show_stripe_cache_size(struct mddev *mddev, char *page)
5867 {
5868         struct r5conf *conf;
5869         int ret = 0;
5870         spin_lock(&mddev->lock);
5871         conf = mddev->private;
5872         if (conf)
5873                 ret = sprintf(page, "%d\n", conf->min_nr_stripes);
5874         spin_unlock(&mddev->lock);
5875         return ret;
5876 }
5877
5878 int
5879 raid5_set_cache_size(struct mddev *mddev, int size)
5880 {
5881         struct r5conf *conf = mddev->private;
5882         int err;
5883
5884         if (size <= 16 || size > 32768)
5885                 return -EINVAL;
5886
5887         conf->min_nr_stripes = size;
5888         while (size < conf->max_nr_stripes &&
5889                drop_one_stripe(conf))
5890                 ;
5891
5892
5893         err = md_allow_write(mddev);
5894         if (err)
5895                 return err;
5896
5897         while (size > conf->max_nr_stripes)
5898                 if (!grow_one_stripe(conf, GFP_KERNEL))
5899                         break;
5900
5901         return 0;
5902 }
5903 EXPORT_SYMBOL(raid5_set_cache_size);
5904
5905 static ssize_t
5906 raid5_store_stripe_cache_size(struct mddev *mddev, const char *page, size_t len)
5907 {
5908         struct r5conf *conf;
5909         unsigned long new;
5910         int err;
5911
5912         if (len >= PAGE_SIZE)
5913                 return -EINVAL;
5914         if (kstrtoul(page, 10, &new))
5915                 return -EINVAL;
5916         err = mddev_lock(mddev);
5917         if (err)
5918                 return err;
5919         conf = mddev->private;
5920         if (!conf)
5921                 err = -ENODEV;
5922         else
5923                 err = raid5_set_cache_size(mddev, new);
5924         mddev_unlock(mddev);
5925
5926         return err ?: len;
5927 }
5928
5929 static struct md_sysfs_entry
5930 raid5_stripecache_size = __ATTR(stripe_cache_size, S_IRUGO | S_IWUSR,
5931                                 raid5_show_stripe_cache_size,
5932                                 raid5_store_stripe_cache_size);
5933
5934 static ssize_t
5935 raid5_show_rmw_level(struct mddev  *mddev, char *page)
5936 {
5937         struct r5conf *conf = mddev->private;
5938         if (conf)
5939                 return sprintf(page, "%d\n", conf->rmw_level);
5940         else
5941                 return 0;
5942 }
5943
5944 static ssize_t
5945 raid5_store_rmw_level(struct mddev  *mddev, const char *page, size_t len)
5946 {
5947         struct r5conf *conf = mddev->private;
5948         unsigned long new;
5949
5950         if (!conf)
5951                 return -ENODEV;
5952
5953         if (len >= PAGE_SIZE)
5954                 return -EINVAL;
5955
5956         if (kstrtoul(page, 10, &new))
5957                 return -EINVAL;
5958
5959         if (new != PARITY_DISABLE_RMW && !raid6_call.xor_syndrome)
5960                 return -EINVAL;
5961
5962         if (new != PARITY_DISABLE_RMW &&
5963             new != PARITY_ENABLE_RMW &&
5964             new != PARITY_PREFER_RMW)
5965                 return -EINVAL;
5966
5967         conf->rmw_level = new;
5968         return len;
5969 }
5970
5971 static struct md_sysfs_entry
5972 raid5_rmw_level = __ATTR(rmw_level, S_IRUGO | S_IWUSR,
5973                          raid5_show_rmw_level,
5974                          raid5_store_rmw_level);
5975
5976
5977 static ssize_t
5978 raid5_show_preread_threshold(struct mddev *mddev, char *page)
5979 {
5980         struct r5conf *conf;
5981         int ret = 0;
5982         spin_lock(&mddev->lock);
5983         conf = mddev->private;
5984         if (conf)
5985                 ret = sprintf(page, "%d\n", conf->bypass_threshold);
5986         spin_unlock(&mddev->lock);
5987         return ret;
5988 }
5989
5990 static ssize_t
5991 raid5_store_preread_threshold(struct mddev *mddev, const char *page, size_t len)
5992 {
5993         struct r5conf *conf;
5994         unsigned long new;
5995         int err;
5996
5997         if (len >= PAGE_SIZE)
5998                 return -EINVAL;
5999         if (kstrtoul(page, 10, &new))
6000                 return -EINVAL;
6001
6002         err = mddev_lock(mddev);
6003         if (err)
6004                 return err;
6005         conf = mddev->private;
6006         if (!conf)
6007                 err = -ENODEV;
6008         else if (new > conf->min_nr_stripes)
6009                 err = -EINVAL;
6010         else
6011                 conf->bypass_threshold = new;
6012         mddev_unlock(mddev);
6013         return err ?: len;
6014 }
6015
6016 static struct md_sysfs_entry
6017 raid5_preread_bypass_threshold = __ATTR(preread_bypass_threshold,
6018                                         S_IRUGO | S_IWUSR,
6019                                         raid5_show_preread_threshold,
6020                                         raid5_store_preread_threshold);
6021
6022 static ssize_t
6023 raid5_show_skip_copy(struct mddev *mddev, char *page)
6024 {
6025         struct r5conf *conf;
6026         int ret = 0;
6027         spin_lock(&mddev->lock);
6028         conf = mddev->private;
6029         if (conf)
6030                 ret = sprintf(page, "%d\n", conf->skip_copy);
6031         spin_unlock(&mddev->lock);
6032         return ret;
6033 }
6034
6035 static ssize_t
6036 raid5_store_skip_copy(struct mddev *mddev, const char *page, size_t len)
6037 {
6038         struct r5conf *conf;
6039         unsigned long new;
6040         int err;
6041
6042         if (len >= PAGE_SIZE)
6043                 return -EINVAL;
6044         if (kstrtoul(page, 10, &new))
6045                 return -EINVAL;
6046         new = !!new;
6047
6048         err = mddev_lock(mddev);
6049         if (err)
6050                 return err;
6051         conf = mddev->private;
6052         if (!conf)
6053                 err = -ENODEV;
6054         else if (new != conf->skip_copy) {
6055                 mddev_suspend(mddev);
6056                 conf->skip_copy = new;
6057                 if (new)
6058                         mddev->queue->backing_dev_info.capabilities |=
6059                                 BDI_CAP_STABLE_WRITES;
6060                 else
6061                         mddev->queue->backing_dev_info.capabilities &=
6062                                 ~BDI_CAP_STABLE_WRITES;
6063                 mddev_resume(mddev);
6064         }
6065         mddev_unlock(mddev);
6066         return err ?: len;
6067 }
6068
6069 static struct md_sysfs_entry
6070 raid5_skip_copy = __ATTR(skip_copy, S_IRUGO | S_IWUSR,
6071                                         raid5_show_skip_copy,
6072                                         raid5_store_skip_copy);
6073
6074 static ssize_t
6075 stripe_cache_active_show(struct mddev *mddev, char *page)
6076 {
6077         struct r5conf *conf = mddev->private;
6078         if (conf)
6079                 return sprintf(page, "%d\n", atomic_read(&conf->active_stripes));
6080         else
6081                 return 0;
6082 }
6083
6084 static struct md_sysfs_entry
6085 raid5_stripecache_active = __ATTR_RO(stripe_cache_active);
6086
6087 static ssize_t
6088 raid5_show_group_thread_cnt(struct mddev *mddev, char *page)
6089 {
6090         struct r5conf *conf;
6091         int ret = 0;
6092         spin_lock(&mddev->lock);
6093         conf = mddev->private;
6094         if (conf)
6095                 ret = sprintf(page, "%d\n", conf->worker_cnt_per_group);
6096         spin_unlock(&mddev->lock);
6097         return ret;
6098 }
6099
6100 static int alloc_thread_groups(struct r5conf *conf, int cnt,
6101                                int *group_cnt,
6102                                int *worker_cnt_per_group,
6103                                struct r5worker_group **worker_groups);
6104 static ssize_t
6105 raid5_store_group_thread_cnt(struct mddev *mddev, const char *page, size_t len)
6106 {
6107         struct r5conf *conf;
6108         unsigned long new;
6109         int err;
6110         struct r5worker_group *new_groups, *old_groups;
6111         int group_cnt, worker_cnt_per_group;
6112
6113         if (len >= PAGE_SIZE)
6114                 return -EINVAL;
6115         if (kstrtoul(page, 10, &new))
6116                 return -EINVAL;
6117
6118         err = mddev_lock(mddev);
6119         if (err)
6120                 return err;
6121         conf = mddev->private;
6122         if (!conf)
6123                 err = -ENODEV;
6124         else if (new != conf->worker_cnt_per_group) {
6125                 mddev_suspend(mddev);
6126
6127                 old_groups = conf->worker_groups;
6128                 if (old_groups)
6129                         flush_workqueue(raid5_wq);
6130
6131                 err = alloc_thread_groups(conf, new,
6132                                           &group_cnt, &worker_cnt_per_group,
6133                                           &new_groups);
6134                 if (!err) {
6135                         spin_lock_irq(&conf->device_lock);
6136                         conf->group_cnt = group_cnt;
6137                         conf->worker_cnt_per_group = worker_cnt_per_group;
6138                         conf->worker_groups = new_groups;
6139                         spin_unlock_irq(&conf->device_lock);
6140
6141                         if (old_groups)
6142                                 kfree(old_groups[0].workers);
6143                         kfree(old_groups);
6144                 }
6145                 mddev_resume(mddev);
6146         }
6147         mddev_unlock(mddev);
6148
6149         return err ?: len;
6150 }
6151
6152 static struct md_sysfs_entry
6153 raid5_group_thread_cnt = __ATTR(group_thread_cnt, S_IRUGO | S_IWUSR,
6154                                 raid5_show_group_thread_cnt,
6155                                 raid5_store_group_thread_cnt);
6156
6157 static struct attribute *raid5_attrs[] =  {
6158         &raid5_stripecache_size.attr,
6159         &raid5_stripecache_active.attr,
6160         &raid5_preread_bypass_threshold.attr,
6161         &raid5_group_thread_cnt.attr,
6162         &raid5_skip_copy.attr,
6163         &raid5_rmw_level.attr,
6164         NULL,
6165 };
6166 static struct attribute_group raid5_attrs_group = {
6167         .name = NULL,
6168         .attrs = raid5_attrs,
6169 };
6170
6171 static int alloc_thread_groups(struct r5conf *conf, int cnt,
6172                                int *group_cnt,
6173                                int *worker_cnt_per_group,
6174                                struct r5worker_group **worker_groups)
6175 {
6176         int i, j, k;
6177         ssize_t size;
6178         struct r5worker *workers;
6179
6180         *worker_cnt_per_group = cnt;
6181         if (cnt == 0) {
6182                 *group_cnt = 0;
6183                 *worker_groups = NULL;
6184                 return 0;
6185         }
6186         *group_cnt = num_possible_nodes();
6187         size = sizeof(struct r5worker) * cnt;
6188         workers = kzalloc(size * *group_cnt, GFP_NOIO);
6189         *worker_groups = kzalloc(sizeof(struct r5worker_group) *
6190                                 *group_cnt, GFP_NOIO);
6191         if (!*worker_groups || !workers) {
6192                 kfree(workers);
6193                 kfree(*worker_groups);
6194                 return -ENOMEM;
6195         }
6196
6197         for (i = 0; i < *group_cnt; i++) {
6198                 struct r5worker_group *group;
6199
6200                 group = &(*worker_groups)[i];
6201                 INIT_LIST_HEAD(&group->handle_list);
6202                 group->conf = conf;
6203                 group->workers = workers + i * cnt;
6204
6205                 for (j = 0; j < cnt; j++) {
6206                         struct r5worker *worker = group->workers + j;
6207                         worker->group = group;
6208                         INIT_WORK(&worker->work, raid5_do_work);
6209
6210                         for (k = 0; k < NR_STRIPE_HASH_LOCKS; k++)
6211                                 INIT_LIST_HEAD(worker->temp_inactive_list + k);
6212                 }
6213         }
6214
6215         return 0;
6216 }
6217
6218 static void free_thread_groups(struct r5conf *conf)
6219 {
6220         if (conf->worker_groups)
6221                 kfree(conf->worker_groups[0].workers);
6222         kfree(conf->worker_groups);
6223         conf->worker_groups = NULL;
6224 }
6225
6226 static sector_t
6227 raid5_size(struct mddev *mddev, sector_t sectors, int raid_disks)
6228 {
6229         struct r5conf *conf = mddev->private;
6230
6231         if (!sectors)
6232                 sectors = mddev->dev_sectors;
6233         if (!raid_disks)
6234                 /* size is defined by the smallest of previous and new size */
6235                 raid_disks = min(conf->raid_disks, conf->previous_raid_disks);
6236
6237         sectors &= ~((sector_t)mddev->chunk_sectors - 1);
6238         sectors &= ~((sector_t)mddev->new_chunk_sectors - 1);
6239         return sectors * (raid_disks - conf->max_degraded);
6240 }
6241
6242 static void free_scratch_buffer(struct r5conf *conf, struct raid5_percpu *percpu)
6243 {
6244         safe_put_page(percpu->spare_page);
6245         if (percpu->scribble)
6246                 flex_array_free(percpu->scribble);
6247         percpu->spare_page = NULL;
6248         percpu->scribble = NULL;
6249 }
6250
6251 static int alloc_scratch_buffer(struct r5conf *conf, struct raid5_percpu *percpu)
6252 {
6253         if (conf->level == 6 && !percpu->spare_page)
6254                 percpu->spare_page = alloc_page(GFP_KERNEL);
6255         if (!percpu->scribble)
6256                 percpu->scribble = scribble_alloc(max(conf->raid_disks,
6257                                                       conf->previous_raid_disks),
6258                                                   max(conf->chunk_sectors,
6259                                                       conf->prev_chunk_sectors)
6260                                                    / STRIPE_SECTORS,
6261                                                   GFP_KERNEL);
6262
6263         if (!percpu->scribble || (conf->level == 6 && !percpu->spare_page)) {
6264                 free_scratch_buffer(conf, percpu);
6265                 return -ENOMEM;
6266         }
6267
6268         return 0;
6269 }
6270
6271 static void raid5_free_percpu(struct r5conf *conf)
6272 {
6273         unsigned long cpu;
6274
6275         if (!conf->percpu)
6276                 return;
6277
6278 #ifdef CONFIG_HOTPLUG_CPU
6279         unregister_cpu_notifier(&conf->cpu_notify);
6280 #endif
6281
6282         get_online_cpus();
6283         for_each_possible_cpu(cpu)
6284                 free_scratch_buffer(conf, per_cpu_ptr(conf->percpu, cpu));
6285         put_online_cpus();
6286
6287         free_percpu(conf->percpu);
6288 }
6289
6290 static void free_conf(struct r5conf *conf)
6291 {
6292         if (conf->shrinker.seeks)
6293                 unregister_shrinker(&conf->shrinker);
6294         free_thread_groups(conf);
6295         shrink_stripes(conf);
6296         raid5_free_percpu(conf);
6297         kfree(conf->disks);
6298         kfree(conf->stripe_hashtbl);
6299         kfree(conf);
6300 }
6301
6302 #ifdef CONFIG_HOTPLUG_CPU
6303 static int raid456_cpu_notify(struct notifier_block *nfb, unsigned long action,
6304                               void *hcpu)
6305 {
6306         struct r5conf *conf = container_of(nfb, struct r5conf, cpu_notify);
6307         long cpu = (long)hcpu;
6308         struct raid5_percpu *percpu = per_cpu_ptr(conf->percpu, cpu);
6309
6310         switch (action) {
6311         case CPU_UP_PREPARE:
6312         case CPU_UP_PREPARE_FROZEN:
6313                 if (alloc_scratch_buffer(conf, percpu)) {
6314                         pr_err("%s: failed memory allocation for cpu%ld\n",
6315                                __func__, cpu);
6316                         return notifier_from_errno(-ENOMEM);
6317                 }
6318                 break;
6319         case CPU_DEAD:
6320         case CPU_DEAD_FROZEN:
6321                 free_scratch_buffer(conf, per_cpu_ptr(conf->percpu, cpu));
6322                 break;
6323         default:
6324                 break;
6325         }
6326         return NOTIFY_OK;
6327 }
6328 #endif
6329
6330 static int raid5_alloc_percpu(struct r5conf *conf)
6331 {
6332         unsigned long cpu;
6333         int err = 0;
6334
6335         conf->percpu = alloc_percpu(struct raid5_percpu);
6336         if (!conf->percpu)
6337                 return -ENOMEM;
6338
6339 #ifdef CONFIG_HOTPLUG_CPU
6340         conf->cpu_notify.notifier_call = raid456_cpu_notify;
6341         conf->cpu_notify.priority = 0;
6342         err = register_cpu_notifier(&conf->cpu_notify);
6343         if (err)
6344                 return err;
6345 #endif
6346
6347         get_online_cpus();
6348         for_each_present_cpu(cpu) {
6349                 err = alloc_scratch_buffer(conf, per_cpu_ptr(conf->percpu, cpu));
6350                 if (err) {
6351                         pr_err("%s: failed memory allocation for cpu%ld\n",
6352                                __func__, cpu);
6353                         break;
6354                 }
6355                 spin_lock_init(&per_cpu_ptr(conf->percpu, cpu)->lock);
6356         }
6357         put_online_cpus();
6358
6359         return err;
6360 }
6361
6362 static unsigned long raid5_cache_scan(struct shrinker *shrink,
6363                                       struct shrink_control *sc)
6364 {
6365         struct r5conf *conf = container_of(shrink, struct r5conf, shrinker);
6366         int ret = 0;
6367         while (ret < sc->nr_to_scan) {
6368                 if (drop_one_stripe(conf) == 0)
6369                         return SHRINK_STOP;
6370                 ret++;
6371         }
6372         return ret;
6373 }
6374
6375 static unsigned long raid5_cache_count(struct shrinker *shrink,
6376                                        struct shrink_control *sc)
6377 {
6378         struct r5conf *conf = container_of(shrink, struct r5conf, shrinker);
6379
6380         if (conf->max_nr_stripes < conf->min_nr_stripes)
6381                 /* unlikely, but not impossible */
6382                 return 0;
6383         return conf->max_nr_stripes - conf->min_nr_stripes;
6384 }
6385
6386 static struct r5conf *setup_conf(struct mddev *mddev)
6387 {
6388         struct r5conf *conf;
6389         int raid_disk, memory, max_disks;
6390         struct md_rdev *rdev;
6391         struct disk_info *disk;
6392         char pers_name[6];
6393         int i;
6394         int group_cnt, worker_cnt_per_group;
6395         struct r5worker_group *new_group;
6396
6397         if (mddev->new_level != 5
6398             && mddev->new_level != 4
6399             && mddev->new_level != 6) {
6400                 printk(KERN_ERR "md/raid:%s: raid level not set to 4/5/6 (%d)\n",
6401                        mdname(mddev), mddev->new_level);
6402                 return ERR_PTR(-EIO);
6403         }
6404         if ((mddev->new_level == 5
6405              && !algorithm_valid_raid5(mddev->new_layout)) ||
6406             (mddev->new_level == 6
6407              && !algorithm_valid_raid6(mddev->new_layout))) {
6408                 printk(KERN_ERR "md/raid:%s: layout %d not supported\n",
6409                        mdname(mddev), mddev->new_layout);
6410                 return ERR_PTR(-EIO);
6411         }
6412         if (mddev->new_level == 6 && mddev->raid_disks < 4) {
6413                 printk(KERN_ERR "md/raid:%s: not enough configured devices (%d, minimum 4)\n",
6414                        mdname(mddev), mddev->raid_disks);
6415                 return ERR_PTR(-EINVAL);
6416         }
6417
6418         if (!mddev->new_chunk_sectors ||
6419             (mddev->new_chunk_sectors << 9) % PAGE_SIZE ||
6420             !is_power_of_2(mddev->new_chunk_sectors)) {
6421                 printk(KERN_ERR "md/raid:%s: invalid chunk size %d\n",
6422                        mdname(mddev), mddev->new_chunk_sectors << 9);
6423                 return ERR_PTR(-EINVAL);
6424         }
6425
6426         conf = kzalloc(sizeof(struct r5conf), GFP_KERNEL);
6427         if (conf == NULL)
6428                 goto abort;
6429         /* Don't enable multi-threading by default*/
6430         if (!alloc_thread_groups(conf, 0, &group_cnt, &worker_cnt_per_group,
6431                                  &new_group)) {
6432                 conf->group_cnt = group_cnt;
6433                 conf->worker_cnt_per_group = worker_cnt_per_group;
6434                 conf->worker_groups = new_group;
6435         } else
6436                 goto abort;
6437         spin_lock_init(&conf->device_lock);
6438         seqcount_init(&conf->gen_lock);
6439         init_waitqueue_head(&conf->wait_for_stripe);
6440         init_waitqueue_head(&conf->wait_for_overlap);
6441         INIT_LIST_HEAD(&conf->handle_list);
6442         INIT_LIST_HEAD(&conf->hold_list);
6443         INIT_LIST_HEAD(&conf->delayed_list);
6444         INIT_LIST_HEAD(&conf->bitmap_list);
6445         init_llist_head(&conf->released_stripes);
6446         atomic_set(&conf->active_stripes, 0);
6447         atomic_set(&conf->preread_active_stripes, 0);
6448         atomic_set(&conf->active_aligned_reads, 0);
6449         conf->bypass_threshold = BYPASS_THRESHOLD;
6450         conf->recovery_disabled = mddev->recovery_disabled - 1;
6451
6452         conf->raid_disks = mddev->raid_disks;
6453         if (mddev->reshape_position == MaxSector)
6454                 conf->previous_raid_disks = mddev->raid_disks;
6455         else
6456                 conf->previous_raid_disks = mddev->raid_disks - mddev->delta_disks;
6457         max_disks = max(conf->raid_disks, conf->previous_raid_disks);
6458
6459         conf->disks = kzalloc(max_disks * sizeof(struct disk_info),
6460                               GFP_KERNEL);
6461         if (!conf->disks)
6462                 goto abort;
6463
6464         conf->mddev = mddev;
6465
6466         if ((conf->stripe_hashtbl = kzalloc(PAGE_SIZE, GFP_KERNEL)) == NULL)
6467                 goto abort;
6468
6469         /* We init hash_locks[0] separately to that it can be used
6470          * as the reference lock in the spin_lock_nest_lock() call
6471          * in lock_all_device_hash_locks_irq in order to convince
6472          * lockdep that we know what we are doing.
6473          */
6474         spin_lock_init(conf->hash_locks);
6475         for (i = 1; i < NR_STRIPE_HASH_LOCKS; i++)
6476                 spin_lock_init(conf->hash_locks + i);
6477
6478         for (i = 0; i < NR_STRIPE_HASH_LOCKS; i++)
6479                 INIT_LIST_HEAD(conf->inactive_list + i);
6480
6481         for (i = 0; i < NR_STRIPE_HASH_LOCKS; i++)
6482                 INIT_LIST_HEAD(conf->temp_inactive_list + i);
6483
6484         conf->level = mddev->new_level;
6485         conf->chunk_sectors = mddev->new_chunk_sectors;
6486         if (raid5_alloc_percpu(conf) != 0)
6487                 goto abort;
6488
6489         pr_debug("raid456: run(%s) called.\n", mdname(mddev));
6490
6491         rdev_for_each(rdev, mddev) {
6492                 raid_disk = rdev->raid_disk;
6493                 if (raid_disk >= max_disks
6494                     || raid_disk < 0)
6495                         continue;
6496                 disk = conf->disks + raid_disk;
6497
6498                 if (test_bit(Replacement, &rdev->flags)) {
6499                         if (disk->replacement)
6500                                 goto abort;
6501                         disk->replacement = rdev;
6502                 } else {
6503                         if (disk->rdev)
6504                                 goto abort;
6505                         disk->rdev = rdev;
6506                 }
6507
6508                 if (test_bit(In_sync, &rdev->flags)) {
6509                         char b[BDEVNAME_SIZE];
6510                         printk(KERN_INFO "md/raid:%s: device %s operational as raid"
6511                                " disk %d\n",
6512                                mdname(mddev), bdevname(rdev->bdev, b), raid_disk);
6513                 } else if (rdev->saved_raid_disk != raid_disk)
6514                         /* Cannot rely on bitmap to complete recovery */
6515                         conf->fullsync = 1;
6516         }
6517
6518         conf->level = mddev->new_level;
6519         if (conf->level == 6) {
6520                 conf->max_degraded = 2;
6521                 if (raid6_call.xor_syndrome)
6522                         conf->rmw_level = PARITY_ENABLE_RMW;
6523                 else
6524                         conf->rmw_level = PARITY_DISABLE_RMW;
6525         } else {
6526                 conf->max_degraded = 1;
6527                 conf->rmw_level = PARITY_ENABLE_RMW;
6528         }
6529         conf->algorithm = mddev->new_layout;
6530         conf->reshape_progress = mddev->reshape_position;
6531         if (conf->reshape_progress != MaxSector) {
6532                 conf->prev_chunk_sectors = mddev->chunk_sectors;
6533                 conf->prev_algo = mddev->layout;
6534         }
6535
6536         conf->min_nr_stripes = NR_STRIPES;
6537         memory = conf->min_nr_stripes * (sizeof(struct stripe_head) +
6538                  max_disks * ((sizeof(struct bio) + PAGE_SIZE))) / 1024;
6539         atomic_set(&conf->empty_inactive_list_nr, NR_STRIPE_HASH_LOCKS);
6540         if (grow_stripes(conf, conf->min_nr_stripes)) {
6541                 printk(KERN_ERR
6542                        "md/raid:%s: couldn't allocate %dkB for buffers\n",
6543                        mdname(mddev), memory);
6544                 goto abort;
6545         } else
6546                 printk(KERN_INFO "md/raid:%s: allocated %dkB\n",
6547                        mdname(mddev), memory);
6548         /*
6549          * Losing a stripe head costs more than the time to refill it,
6550          * it reduces the queue depth and so can hurt throughput.
6551          * So set it rather large, scaled by number of devices.
6552          */
6553         conf->shrinker.seeks = DEFAULT_SEEKS * conf->raid_disks * 4;
6554         conf->shrinker.scan_objects = raid5_cache_scan;
6555         conf->shrinker.count_objects = raid5_cache_count;
6556         conf->shrinker.batch = 128;
6557         conf->shrinker.flags = 0;
6558         register_shrinker(&conf->shrinker);
6559
6560         sprintf(pers_name, "raid%d", mddev->new_level);
6561         conf->thread = md_register_thread(raid5d, mddev, pers_name);
6562         if (!conf->thread) {
6563                 printk(KERN_ERR
6564                        "md/raid:%s: couldn't allocate thread.\n",
6565                        mdname(mddev));
6566                 goto abort;
6567         }
6568
6569         return conf;
6570
6571  abort:
6572         if (conf) {
6573                 free_conf(conf);
6574                 return ERR_PTR(-EIO);
6575         } else
6576                 return ERR_PTR(-ENOMEM);
6577 }
6578
6579 static int only_parity(int raid_disk, int algo, int raid_disks, int max_degraded)
6580 {
6581         switch (algo) {
6582         case ALGORITHM_PARITY_0:
6583                 if (raid_disk < max_degraded)
6584                         return 1;
6585                 break;
6586         case ALGORITHM_PARITY_N:
6587                 if (raid_disk >= raid_disks - max_degraded)
6588                         return 1;
6589                 break;
6590         case ALGORITHM_PARITY_0_6:
6591                 if (raid_disk == 0 ||
6592                     raid_disk == raid_disks - 1)
6593                         return 1;
6594                 break;
6595         case ALGORITHM_LEFT_ASYMMETRIC_6:
6596         case ALGORITHM_RIGHT_ASYMMETRIC_6:
6597         case ALGORITHM_LEFT_SYMMETRIC_6:
6598         case ALGORITHM_RIGHT_SYMMETRIC_6:
6599                 if (raid_disk == raid_disks - 1)
6600                         return 1;
6601         }
6602         return 0;
6603 }
6604
6605 static int run(struct mddev *mddev)
6606 {
6607         struct r5conf *conf;
6608         int working_disks = 0;
6609         int dirty_parity_disks = 0;
6610         struct md_rdev *rdev;
6611         sector_t reshape_offset = 0;
6612         int i;
6613         long long min_offset_diff = 0;
6614         int first = 1;
6615
6616         if (mddev->recovery_cp != MaxSector)
6617                 printk(KERN_NOTICE "md/raid:%s: not clean"
6618                        " -- starting background reconstruction\n",
6619                        mdname(mddev));
6620
6621         rdev_for_each(rdev, mddev) {
6622                 long long diff;
6623                 if (rdev->raid_disk < 0)
6624                         continue;
6625                 diff = (rdev->new_data_offset - rdev->data_offset);
6626                 if (first) {
6627                         min_offset_diff = diff;
6628                         first = 0;
6629                 } else if (mddev->reshape_backwards &&
6630                          diff < min_offset_diff)
6631                         min_offset_diff = diff;
6632                 else if (!mddev->reshape_backwards &&
6633                          diff > min_offset_diff)
6634                         min_offset_diff = diff;
6635         }
6636
6637         if (mddev->reshape_position != MaxSector) {
6638                 /* Check that we can continue the reshape.
6639                  * Difficulties arise if the stripe we would write to
6640                  * next is at or after the stripe we would read from next.
6641                  * For a reshape that changes the number of devices, this
6642                  * is only possible for a very short time, and mdadm makes
6643                  * sure that time appears to have past before assembling
6644                  * the array.  So we fail if that time hasn't passed.
6645                  * For a reshape that keeps the number of devices the same
6646                  * mdadm must be monitoring the reshape can keeping the
6647                  * critical areas read-only and backed up.  It will start
6648                  * the array in read-only mode, so we check for that.
6649                  */
6650                 sector_t here_new, here_old;
6651                 int old_disks;
6652                 int max_degraded = (mddev->level == 6 ? 2 : 1);
6653
6654                 if (mddev->new_level != mddev->level) {
6655                         printk(KERN_ERR "md/raid:%s: unsupported reshape "
6656                                "required - aborting.\n",
6657                                mdname(mddev));
6658                         return -EINVAL;
6659                 }
6660                 old_disks = mddev->raid_disks - mddev->delta_disks;
6661                 /* reshape_position must be on a new-stripe boundary, and one
6662                  * further up in new geometry must map after here in old
6663                  * geometry.
6664                  */
6665                 here_new = mddev->reshape_position;
6666                 if (sector_div(here_new, mddev->new_chunk_sectors *
6667                                (mddev->raid_disks - max_degraded))) {
6668                         printk(KERN_ERR "md/raid:%s: reshape_position not "
6669                                "on a stripe boundary\n", mdname(mddev));
6670                         return -EINVAL;
6671                 }
6672                 reshape_offset = here_new * mddev->new_chunk_sectors;
6673                 /* here_new is the stripe we will write to */
6674                 here_old = mddev->reshape_position;
6675                 sector_div(here_old, mddev->chunk_sectors *
6676                            (old_disks-max_degraded));
6677                 /* here_old is the first stripe that we might need to read
6678                  * from */
6679                 if (mddev->delta_disks == 0) {
6680                         if ((here_new * mddev->new_chunk_sectors !=
6681                              here_old * mddev->chunk_sectors)) {
6682                                 printk(KERN_ERR "md/raid:%s: reshape position is"
6683                                        " confused - aborting\n", mdname(mddev));
6684                                 return -EINVAL;
6685                         }
6686                         /* We cannot be sure it is safe to start an in-place
6687                          * reshape.  It is only safe if user-space is monitoring
6688                          * and taking constant backups.
6689                          * mdadm always starts a situation like this in
6690                          * readonly mode so it can take control before
6691                          * allowing any writes.  So just check for that.
6692                          */
6693                         if (abs(min_offset_diff) >= mddev->chunk_sectors &&
6694                             abs(min_offset_diff) >= mddev->new_chunk_sectors)
6695                                 /* not really in-place - so OK */;
6696                         else if (mddev->ro == 0) {
6697                                 printk(KERN_ERR "md/raid:%s: in-place reshape "
6698                                        "must be started in read-only mode "
6699                                        "- aborting\n",
6700                                        mdname(mddev));
6701                                 return -EINVAL;
6702                         }
6703                 } else if (mddev->reshape_backwards
6704                     ? (here_new * mddev->new_chunk_sectors + min_offset_diff <=
6705                        here_old * mddev->chunk_sectors)
6706                     : (here_new * mddev->new_chunk_sectors >=
6707                        here_old * mddev->chunk_sectors + (-min_offset_diff))) {
6708                         /* Reading from the same stripe as writing to - bad */
6709                         printk(KERN_ERR "md/raid:%s: reshape_position too early for "
6710                                "auto-recovery - aborting.\n",
6711                                mdname(mddev));
6712                         return -EINVAL;
6713                 }
6714                 printk(KERN_INFO "md/raid:%s: reshape will continue\n",
6715                        mdname(mddev));
6716                 /* OK, we should be able to continue; */
6717         } else {
6718                 BUG_ON(mddev->level != mddev->new_level);
6719                 BUG_ON(mddev->layout != mddev->new_layout);
6720                 BUG_ON(mddev->chunk_sectors != mddev->new_chunk_sectors);
6721                 BUG_ON(mddev->delta_disks != 0);
6722         }
6723
6724         if (mddev->private == NULL)
6725                 conf = setup_conf(mddev);
6726         else
6727                 conf = mddev->private;
6728
6729         if (IS_ERR(conf))
6730                 return PTR_ERR(conf);
6731
6732         conf->min_offset_diff = min_offset_diff;
6733         mddev->thread = conf->thread;
6734         conf->thread = NULL;
6735         mddev->private = conf;
6736
6737         for (i = 0; i < conf->raid_disks && conf->previous_raid_disks;
6738              i++) {
6739                 rdev = conf->disks[i].rdev;
6740                 if (!rdev && conf->disks[i].replacement) {
6741                         /* The replacement is all we have yet */
6742                         rdev = conf->disks[i].replacement;
6743                         conf->disks[i].replacement = NULL;
6744                         clear_bit(Replacement, &rdev->flags);
6745                         conf->disks[i].rdev = rdev;
6746                 }
6747                 if (!rdev)
6748                         continue;
6749                 if (conf->disks[i].replacement &&
6750                     conf->reshape_progress != MaxSector) {
6751                         /* replacements and reshape simply do not mix. */
6752                         printk(KERN_ERR "md: cannot handle concurrent "
6753                                "replacement and reshape.\n");
6754                         goto abort;
6755                 }
6756                 if (test_bit(In_sync, &rdev->flags)) {
6757                         working_disks++;
6758                         continue;
6759                 }
6760                 /* This disc is not fully in-sync.  However if it
6761                  * just stored parity (beyond the recovery_offset),
6762                  * when we don't need to be concerned about the
6763                  * array being dirty.
6764                  * When reshape goes 'backwards', we never have
6765                  * partially completed devices, so we only need
6766                  * to worry about reshape going forwards.
6767                  */
6768                 /* Hack because v0.91 doesn't store recovery_offset properly. */
6769                 if (mddev->major_version == 0 &&
6770                     mddev->minor_version > 90)
6771                         rdev->recovery_offset = reshape_offset;
6772
6773                 if (rdev->recovery_offset < reshape_offset) {
6774                         /* We need to check old and new layout */
6775                         if (!only_parity(rdev->raid_disk,
6776                                          conf->algorithm,
6777                                          conf->raid_disks,
6778                                          conf->max_degraded))
6779                                 continue;
6780                 }
6781                 if (!only_parity(rdev->raid_disk,
6782                                  conf->prev_algo,
6783                                  conf->previous_raid_disks,
6784                                  conf->max_degraded))
6785                         continue;
6786                 dirty_parity_disks++;
6787         }
6788
6789         /*
6790          * 0 for a fully functional array, 1 or 2 for a degraded array.
6791          */
6792         mddev->degraded = calc_degraded(conf);
6793
6794         if (has_failed(conf)) {
6795                 printk(KERN_ERR "md/raid:%s: not enough operational devices"
6796                         " (%d/%d failed)\n",
6797                         mdname(mddev), mddev->degraded, conf->raid_disks);
6798                 goto abort;
6799         }
6800
6801         /* device size must be a multiple of chunk size */
6802         mddev->dev_sectors &= ~(mddev->chunk_sectors - 1);
6803         mddev->resync_max_sectors = mddev->dev_sectors;
6804
6805         if (mddev->degraded > dirty_parity_disks &&
6806             mddev->recovery_cp != MaxSector) {
6807                 if (mddev->ok_start_degraded)
6808                         printk(KERN_WARNING
6809                                "md/raid:%s: starting dirty degraded array"
6810                                " - data corruption possible.\n",
6811                                mdname(mddev));
6812                 else {
6813                         printk(KERN_ERR
6814                                "md/raid:%s: cannot start dirty degraded array.\n",
6815                                mdname(mddev));
6816                         goto abort;
6817                 }
6818         }
6819
6820         if (mddev->degraded == 0)
6821                 printk(KERN_INFO "md/raid:%s: raid level %d active with %d out of %d"
6822                        " devices, algorithm %d\n", mdname(mddev), conf->level,
6823                        mddev->raid_disks-mddev->degraded, mddev->raid_disks,
6824                        mddev->new_layout);
6825         else
6826                 printk(KERN_ALERT "md/raid:%s: raid level %d active with %d"
6827                        " out of %d devices, algorithm %d\n",
6828                        mdname(mddev), conf->level,
6829                        mddev->raid_disks - mddev->degraded,
6830                        mddev->raid_disks, mddev->new_layout);
6831
6832         print_raid5_conf(conf);
6833
6834         if (conf->reshape_progress != MaxSector) {
6835                 conf->reshape_safe = conf->reshape_progress;
6836                 atomic_set(&conf->reshape_stripes, 0);
6837                 clear_bit(MD_RECOVERY_SYNC, &mddev->recovery);
6838                 clear_bit(MD_RECOVERY_CHECK, &mddev->recovery);
6839                 set_bit(MD_RECOVERY_RESHAPE, &mddev->recovery);
6840                 set_bit(MD_RECOVERY_RUNNING, &mddev->recovery);
6841                 mddev->sync_thread = md_register_thread(md_do_sync, mddev,
6842                                                         "reshape");
6843         }
6844
6845         /* Ok, everything is just fine now */
6846         if (mddev->to_remove == &raid5_attrs_group)
6847                 mddev->to_remove = NULL;
6848         else if (mddev->kobj.sd &&
6849             sysfs_create_group(&mddev->kobj, &raid5_attrs_group))
6850                 printk(KERN_WARNING
6851                        "raid5: failed to create sysfs attributes for %s\n",
6852                        mdname(mddev));
6853         md_set_array_sectors(mddev, raid5_size(mddev, 0, 0));
6854
6855         if (mddev->queue) {
6856                 int chunk_size;
6857                 bool discard_supported = true;
6858                 /* read-ahead size must cover two whole stripes, which
6859                  * is 2 * (datadisks) * chunksize where 'n' is the
6860                  * number of raid devices
6861                  */
6862                 int data_disks = conf->previous_raid_disks - conf->max_degraded;
6863                 int stripe = data_disks *
6864                         ((mddev->chunk_sectors << 9) / PAGE_SIZE);
6865                 if (mddev->queue->backing_dev_info.ra_pages < 2 * stripe)
6866                         mddev->queue->backing_dev_info.ra_pages = 2 * stripe;
6867
6868                 chunk_size = mddev->chunk_sectors << 9;
6869                 blk_queue_io_min(mddev->queue, chunk_size);
6870                 blk_queue_io_opt(mddev->queue, chunk_size *
6871                                  (conf->raid_disks - conf->max_degraded));
6872                 mddev->queue->limits.raid_partial_stripes_expensive = 1;
6873                 /*
6874                  * We can only discard a whole stripe. It doesn't make sense to
6875                  * discard data disk but write parity disk
6876                  */
6877                 stripe = stripe * PAGE_SIZE;
6878                 /* Round up to power of 2, as discard handling
6879                  * currently assumes that */
6880                 while ((stripe-1) & stripe)
6881                         stripe = (stripe | (stripe-1)) + 1;
6882                 mddev->queue->limits.discard_alignment = stripe;
6883                 mddev->queue->limits.discard_granularity = stripe;
6884                 /*
6885                  * unaligned part of discard request will be ignored, so can't
6886                  * guarantee discard_zeroes_data
6887                  */
6888                 mddev->queue->limits.discard_zeroes_data = 0;
6889
6890                 blk_queue_max_write_same_sectors(mddev->queue, 0);
6891
6892                 rdev_for_each(rdev, mddev) {
6893                         disk_stack_limits(mddev->gendisk, rdev->bdev,
6894                                           rdev->data_offset << 9);
6895                         disk_stack_limits(mddev->gendisk, rdev->bdev,
6896                                           rdev->new_data_offset << 9);
6897                         /*
6898                          * discard_zeroes_data is required, otherwise data
6899                          * could be lost. Consider a scenario: discard a stripe
6900                          * (the stripe could be inconsistent if
6901                          * discard_zeroes_data is 0); write one disk of the
6902                          * stripe (the stripe could be inconsistent again
6903                          * depending on which disks are used to calculate
6904                          * parity); the disk is broken; The stripe data of this
6905                          * disk is lost.
6906                          */
6907                         if (!blk_queue_discard(bdev_get_queue(rdev->bdev)) ||
6908                             !bdev_get_queue(rdev->bdev)->
6909                                                 limits.discard_zeroes_data)
6910                                 discard_supported = false;
6911                         /* Unfortunately, discard_zeroes_data is not currently
6912                          * a guarantee - just a hint.  So we only allow DISCARD
6913                          * if the sysadmin has confirmed that only safe devices
6914                          * are in use by setting a module parameter.
6915                          */
6916                         if (!devices_handle_discard_safely) {
6917                                 if (discard_supported) {
6918                                         pr_info("md/raid456: discard support disabled due to uncertainty.\n");
6919                                         pr_info("Set raid456.devices_handle_discard_safely=Y to override.\n");
6920                                 }
6921                                 discard_supported = false;
6922                         }
6923                 }
6924
6925                 if (discard_supported &&
6926                    mddev->queue->limits.max_discard_sectors >= stripe &&
6927                    mddev->queue->limits.discard_granularity >= stripe)
6928                         queue_flag_set_unlocked(QUEUE_FLAG_DISCARD,
6929                                                 mddev->queue);
6930                 else
6931                         queue_flag_clear_unlocked(QUEUE_FLAG_DISCARD,
6932                                                 mddev->queue);
6933         }
6934
6935         return 0;
6936 abort:
6937         md_unregister_thread(&mddev->thread);
6938         print_raid5_conf(conf);
6939         free_conf(conf);
6940         mddev->private = NULL;
6941         printk(KERN_ALERT "md/raid:%s: failed to run raid set.\n", mdname(mddev));
6942         return -EIO;
6943 }
6944
6945 static void raid5_free(struct mddev *mddev, void *priv)
6946 {
6947         struct r5conf *conf = priv;
6948
6949         free_conf(conf);
6950         mddev->to_remove = &raid5_attrs_group;
6951 }
6952
6953 static void status(struct seq_file *seq, struct mddev *mddev)
6954 {
6955         struct r5conf *conf = mddev->private;
6956         int i;
6957
6958         seq_printf(seq, " level %d, %dk chunk, algorithm %d", mddev->level,
6959                 mddev->chunk_sectors / 2, mddev->layout);
6960         seq_printf (seq, " [%d/%d] [", conf->raid_disks, conf->raid_disks - mddev->degraded);
6961         for (i = 0; i < conf->raid_disks; i++)
6962                 seq_printf (seq, "%s",
6963                                conf->disks[i].rdev &&
6964                                test_bit(In_sync, &conf->disks[i].rdev->flags) ? "U" : "_");
6965         seq_printf (seq, "]");
6966 }
6967
6968 static void print_raid5_conf (struct r5conf *conf)
6969 {
6970         int i;
6971         struct disk_info *tmp;
6972
6973         printk(KERN_DEBUG "RAID conf printout:\n");
6974         if (!conf) {
6975                 printk("(conf==NULL)\n");
6976                 return;
6977         }
6978         printk(KERN_DEBUG " --- level:%d rd:%d wd:%d\n", conf->level,
6979                conf->raid_disks,
6980                conf->raid_disks - conf->mddev->degraded);
6981
6982         for (i = 0; i < conf->raid_disks; i++) {
6983                 char b[BDEVNAME_SIZE];
6984                 tmp = conf->disks + i;
6985                 if (tmp->rdev)
6986                         printk(KERN_DEBUG " disk %d, o:%d, dev:%s\n",
6987                                i, !test_bit(Faulty, &tmp->rdev->flags),
6988                                bdevname(tmp->rdev->bdev, b));
6989         }
6990 }
6991
6992 static int raid5_spare_active(struct mddev *mddev)
6993 {
6994         int i;
6995         struct r5conf *conf = mddev->private;
6996         struct disk_info *tmp;
6997         int count = 0;
6998         unsigned long flags;
6999
7000         for (i = 0; i < conf->raid_disks; i++) {
7001                 tmp = conf->disks + i;
7002                 if (tmp->replacement
7003                     && tmp->replacement->recovery_offset == MaxSector
7004                     && !test_bit(Faulty, &tmp->replacement->flags)
7005                     && !test_and_set_bit(In_sync, &tmp->replacement->flags)) {
7006                         /* Replacement has just become active. */
7007                         if (!tmp->rdev
7008                             || !test_and_clear_bit(In_sync, &tmp->rdev->flags))
7009                                 count++;
7010                         if (tmp->rdev) {
7011                                 /* Replaced device not technically faulty,
7012                                  * but we need to be sure it gets removed
7013                                  * and never re-added.
7014                                  */
7015                                 set_bit(Faulty, &tmp->rdev->flags);
7016                                 sysfs_notify_dirent_safe(
7017                                         tmp->rdev->sysfs_state);
7018                         }
7019                         sysfs_notify_dirent_safe(tmp->replacement->sysfs_state);
7020                 } else if (tmp->rdev
7021                     && tmp->rdev->recovery_offset == MaxSector
7022                     && !test_bit(Faulty, &tmp->rdev->flags)
7023                     && !test_and_set_bit(In_sync, &tmp->rdev->flags)) {
7024                         count++;
7025                         sysfs_notify_dirent_safe(tmp->rdev->sysfs_state);
7026                 }
7027         }
7028         spin_lock_irqsave(&conf->device_lock, flags);
7029         mddev->degraded = calc_degraded(conf);
7030         spin_unlock_irqrestore(&conf->device_lock, flags);
7031         print_raid5_conf(conf);
7032         return count;
7033 }
7034
7035 static int raid5_remove_disk(struct mddev *mddev, struct md_rdev *rdev)
7036 {
7037         struct r5conf *conf = mddev->private;
7038         int err = 0;
7039         int number = rdev->raid_disk;
7040         struct md_rdev **rdevp;
7041         struct disk_info *p = conf->disks + number;
7042
7043         print_raid5_conf(conf);
7044         if (rdev == p->rdev)
7045                 rdevp = &p->rdev;
7046         else if (rdev == p->replacement)
7047                 rdevp = &p->replacement;
7048         else
7049                 return 0;
7050
7051         if (number >= conf->raid_disks &&
7052             conf->reshape_progress == MaxSector)
7053                 clear_bit(In_sync, &rdev->flags);
7054
7055         if (test_bit(In_sync, &rdev->flags) ||
7056             atomic_read(&rdev->nr_pending)) {
7057                 err = -EBUSY;
7058                 goto abort;
7059         }
7060         /* Only remove non-faulty devices if recovery
7061          * isn't possible.
7062          */
7063         if (!test_bit(Faulty, &rdev->flags) &&
7064             mddev->recovery_disabled != conf->recovery_disabled &&
7065             !has_failed(conf) &&
7066             (!p->replacement || p->replacement == rdev) &&
7067             number < conf->raid_disks) {
7068                 err = -EBUSY;
7069                 goto abort;
7070         }
7071         *rdevp = NULL;
7072         synchronize_rcu();
7073         if (atomic_read(&rdev->nr_pending)) {
7074                 /* lost the race, try later */
7075                 err = -EBUSY;
7076                 *rdevp = rdev;
7077         } else if (p->replacement) {
7078                 /* We must have just cleared 'rdev' */
7079                 p->rdev = p->replacement;
7080                 clear_bit(Replacement, &p->replacement->flags);
7081                 smp_mb(); /* Make sure other CPUs may see both as identical
7082                            * but will never see neither - if they are careful
7083                            */
7084                 p->replacement = NULL;
7085                 clear_bit(WantReplacement, &rdev->flags);
7086         } else
7087                 /* We might have just removed the Replacement as faulty-
7088                  * clear the bit just in case
7089                  */
7090                 clear_bit(WantReplacement, &rdev->flags);
7091 abort:
7092
7093         print_raid5_conf(conf);
7094         return err;
7095 }
7096
7097 static int raid5_add_disk(struct mddev *mddev, struct md_rdev *rdev)
7098 {
7099         struct r5conf *conf = mddev->private;
7100         int err = -EEXIST;
7101         int disk;
7102         struct disk_info *p;
7103         int first = 0;
7104         int last = conf->raid_disks - 1;
7105
7106         if (mddev->recovery_disabled == conf->recovery_disabled)
7107                 return -EBUSY;
7108
7109         if (rdev->saved_raid_disk < 0 && has_failed(conf))
7110                 /* no point adding a device */
7111                 return -EINVAL;
7112
7113         if (rdev->raid_disk >= 0)
7114                 first = last = rdev->raid_disk;
7115
7116         /*
7117          * find the disk ... but prefer rdev->saved_raid_disk
7118          * if possible.
7119          */
7120         if (rdev->saved_raid_disk >= 0 &&
7121             rdev->saved_raid_disk >= first &&
7122             conf->disks[rdev->saved_raid_disk].rdev == NULL)
7123                 first = rdev->saved_raid_disk;
7124
7125         for (disk = first; disk <= last; disk++) {
7126                 p = conf->disks + disk;
7127                 if (p->rdev == NULL) {
7128                         clear_bit(In_sync, &rdev->flags);
7129                         rdev->raid_disk = disk;
7130                         err = 0;
7131                         if (rdev->saved_raid_disk != disk)
7132                                 conf->fullsync = 1;
7133                         rcu_assign_pointer(p->rdev, rdev);
7134                         goto out;
7135                 }
7136         }
7137         for (disk = first; disk <= last; disk++) {
7138                 p = conf->disks + disk;
7139                 if (test_bit(WantReplacement, &p->rdev->flags) &&
7140                     p->replacement == NULL) {
7141                         clear_bit(In_sync, &rdev->flags);
7142                         set_bit(Replacement, &rdev->flags);
7143                         rdev->raid_disk = disk;
7144                         err = 0;
7145                         conf->fullsync = 1;
7146                         rcu_assign_pointer(p->replacement, rdev);
7147                         break;
7148                 }
7149         }
7150 out:
7151         print_raid5_conf(conf);
7152         return err;
7153 }
7154
7155 static int raid5_resize(struct mddev *mddev, sector_t sectors)
7156 {
7157         /* no resync is happening, and there is enough space
7158          * on all devices, so we can resize.
7159          * We need to make sure resync covers any new space.
7160          * If the array is shrinking we should possibly wait until
7161          * any io in the removed space completes, but it hardly seems
7162          * worth it.
7163          */
7164         sector_t newsize;
7165         sectors &= ~((sector_t)mddev->chunk_sectors - 1);
7166         newsize = raid5_size(mddev, sectors, mddev->raid_disks);
7167         if (mddev->external_size &&
7168             mddev->array_sectors > newsize)
7169                 return -EINVAL;
7170         if (mddev->bitmap) {
7171                 int ret = bitmap_resize(mddev->bitmap, sectors, 0, 0);
7172                 if (ret)
7173                         return ret;
7174         }
7175         md_set_array_sectors(mddev, newsize);
7176         set_capacity(mddev->gendisk, mddev->array_sectors);
7177         revalidate_disk(mddev->gendisk);
7178         if (sectors > mddev->dev_sectors &&
7179             mddev->recovery_cp > mddev->dev_sectors) {
7180                 mddev->recovery_cp = mddev->dev_sectors;
7181                 set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
7182         }
7183         mddev->dev_sectors = sectors;
7184         mddev->resync_max_sectors = sectors;
7185         return 0;
7186 }
7187
7188 static int check_stripe_cache(struct mddev *mddev)
7189 {
7190         /* Can only proceed if there are plenty of stripe_heads.
7191          * We need a minimum of one full stripe,, and for sensible progress
7192          * it is best to have about 4 times that.
7193          * If we require 4 times, then the default 256 4K stripe_heads will
7194          * allow for chunk sizes up to 256K, which is probably OK.
7195          * If the chunk size is greater, user-space should request more
7196          * stripe_heads first.
7197          */
7198         struct r5conf *conf = mddev->private;
7199         if (((mddev->chunk_sectors << 9) / STRIPE_SIZE) * 4
7200             > conf->min_nr_stripes ||
7201             ((mddev->new_chunk_sectors << 9) / STRIPE_SIZE) * 4
7202             > conf->min_nr_stripes) {
7203                 printk(KERN_WARNING "md/raid:%s: reshape: not enough stripes.  Needed %lu\n",
7204                        mdname(mddev),
7205                        ((max(mddev->chunk_sectors, mddev->new_chunk_sectors) << 9)
7206                         / STRIPE_SIZE)*4);
7207                 return 0;
7208         }
7209         return 1;
7210 }
7211
7212 static int check_reshape(struct mddev *mddev)
7213 {
7214         struct r5conf *conf = mddev->private;
7215
7216         if (mddev->delta_disks == 0 &&
7217             mddev->new_layout == mddev->layout &&
7218             mddev->new_chunk_sectors == mddev->chunk_sectors)
7219                 return 0; /* nothing to do */
7220         if (has_failed(conf))
7221                 return -EINVAL;
7222         if (mddev->delta_disks < 0 && mddev->reshape_position == MaxSector) {
7223                 /* We might be able to shrink, but the devices must
7224                  * be made bigger first.
7225                  * For raid6, 4 is the minimum size.
7226                  * Otherwise 2 is the minimum
7227                  */
7228                 int min = 2;
7229                 if (mddev->level == 6)
7230                         min = 4;
7231                 if (mddev->raid_disks + mddev->delta_disks < min)
7232                         return -EINVAL;
7233         }
7234
7235         if (!check_stripe_cache(mddev))
7236                 return -ENOSPC;
7237
7238         if (mddev->new_chunk_sectors > mddev->chunk_sectors ||
7239             mddev->delta_disks > 0)
7240                 if (resize_chunks(conf,
7241                                   conf->previous_raid_disks
7242                                   + max(0, mddev->delta_disks),
7243                                   max(mddev->new_chunk_sectors,
7244                                       mddev->chunk_sectors)
7245                             ) < 0)
7246                         return -ENOMEM;
7247         return resize_stripes(conf, (conf->previous_raid_disks
7248                                      + mddev->delta_disks));
7249 }
7250
7251 static int raid5_start_reshape(struct mddev *mddev)
7252 {
7253         struct r5conf *conf = mddev->private;
7254         struct md_rdev *rdev;
7255         int spares = 0;
7256         unsigned long flags;
7257
7258         if (test_bit(MD_RECOVERY_RUNNING, &mddev->recovery))
7259                 return -EBUSY;
7260
7261         if (!check_stripe_cache(mddev))
7262                 return -ENOSPC;
7263
7264         if (has_failed(conf))
7265                 return -EINVAL;
7266
7267         rdev_for_each(rdev, mddev) {
7268                 if (!test_bit(In_sync, &rdev->flags)
7269                     && !test_bit(Faulty, &rdev->flags))
7270                         spares++;
7271         }
7272
7273         if (spares - mddev->degraded < mddev->delta_disks - conf->max_degraded)
7274                 /* Not enough devices even to make a degraded array
7275                  * of that size
7276                  */
7277                 return -EINVAL;
7278
7279         /* Refuse to reduce size of the array.  Any reductions in
7280          * array size must be through explicit setting of array_size
7281          * attribute.
7282          */
7283         if (raid5_size(mddev, 0, conf->raid_disks + mddev->delta_disks)
7284             < mddev->array_sectors) {
7285                 printk(KERN_ERR "md/raid:%s: array size must be reduced "
7286                        "before number of disks\n", mdname(mddev));
7287                 return -EINVAL;
7288         }
7289
7290         atomic_set(&conf->reshape_stripes, 0);
7291         spin_lock_irq(&conf->device_lock);
7292         write_seqcount_begin(&conf->gen_lock);
7293         conf->previous_raid_disks = conf->raid_disks;
7294         conf->raid_disks += mddev->delta_disks;
7295         conf->prev_chunk_sectors = conf->chunk_sectors;
7296         conf->chunk_sectors = mddev->new_chunk_sectors;
7297         conf->prev_algo = conf->algorithm;
7298         conf->algorithm = mddev->new_layout;
7299         conf->generation++;
7300         /* Code that selects data_offset needs to see the generation update
7301          * if reshape_progress has been set - so a memory barrier needed.
7302          */
7303         smp_mb();
7304         if (mddev->reshape_backwards)
7305                 conf->reshape_progress = raid5_size(mddev, 0, 0);
7306         else
7307                 conf->reshape_progress = 0;
7308         conf->reshape_safe = conf->reshape_progress;
7309         write_seqcount_end(&conf->gen_lock);
7310         spin_unlock_irq(&conf->device_lock);
7311
7312         /* Now make sure any requests that proceeded on the assumption
7313          * the reshape wasn't running - like Discard or Read - have
7314          * completed.
7315          */
7316         mddev_suspend(mddev);
7317         mddev_resume(mddev);
7318
7319         /* Add some new drives, as many as will fit.
7320          * We know there are enough to make the newly sized array work.
7321          * Don't add devices if we are reducing the number of
7322          * devices in the array.  This is because it is not possible
7323          * to correctly record the "partially reconstructed" state of
7324          * such devices during the reshape and confusion could result.
7325          */
7326         if (mddev->delta_disks >= 0) {
7327                 rdev_for_each(rdev, mddev)
7328                         if (rdev->raid_disk < 0 &&
7329                             !test_bit(Faulty, &rdev->flags)) {
7330                                 if (raid5_add_disk(mddev, rdev) == 0) {
7331                                         if (rdev->raid_disk
7332                                             >= conf->previous_raid_disks)
7333                                                 set_bit(In_sync, &rdev->flags);
7334                                         else
7335                                                 rdev->recovery_offset = 0;
7336
7337                                         if (sysfs_link_rdev(mddev, rdev))
7338                                                 /* Failure here is OK */;
7339                                 }
7340                         } else if (rdev->raid_disk >= conf->previous_raid_disks
7341                                    && !test_bit(Faulty, &rdev->flags)) {
7342                                 /* This is a spare that was manually added */
7343                                 set_bit(In_sync, &rdev->flags);
7344                         }
7345
7346                 /* When a reshape changes the number of devices,
7347                  * ->degraded is measured against the larger of the
7348                  * pre and post number of devices.
7349                  */
7350                 spin_lock_irqsave(&conf->device_lock, flags);
7351                 mddev->degraded = calc_degraded(conf);
7352                 spin_unlock_irqrestore(&conf->device_lock, flags);
7353         }
7354         mddev->raid_disks = conf->raid_disks;
7355         mddev->reshape_position = conf->reshape_progress;
7356         set_bit(MD_CHANGE_DEVS, &mddev->flags);
7357
7358         clear_bit(MD_RECOVERY_SYNC, &mddev->recovery);
7359         clear_bit(MD_RECOVERY_CHECK, &mddev->recovery);
7360         clear_bit(MD_RECOVERY_DONE, &mddev->recovery);
7361         set_bit(MD_RECOVERY_RESHAPE, &mddev->recovery);
7362         set_bit(MD_RECOVERY_RUNNING, &mddev->recovery);
7363         mddev->sync_thread = md_register_thread(md_do_sync, mddev,
7364                                                 "reshape");
7365         if (!mddev->sync_thread) {
7366                 mddev->recovery = 0;
7367                 spin_lock_irq(&conf->device_lock);
7368                 write_seqcount_begin(&conf->gen_lock);
7369                 mddev->raid_disks = conf->raid_disks = conf->previous_raid_disks;
7370                 mddev->new_chunk_sectors =
7371                         conf->chunk_sectors = conf->prev_chunk_sectors;
7372                 mddev->new_layout = conf->algorithm = conf->prev_algo;
7373                 rdev_for_each(rdev, mddev)
7374                         rdev->new_data_offset = rdev->data_offset;
7375                 smp_wmb();
7376                 conf->generation --;
7377                 conf->reshape_progress = MaxSector;
7378                 mddev->reshape_position = MaxSector;
7379                 write_seqcount_end(&conf->gen_lock);
7380                 spin_unlock_irq(&conf->device_lock);
7381                 return -EAGAIN;
7382         }
7383         conf->reshape_checkpoint = jiffies;
7384         md_wakeup_thread(mddev->sync_thread);
7385         md_new_event(mddev);
7386         return 0;
7387 }
7388
7389 /* This is called from the reshape thread and should make any
7390  * changes needed in 'conf'
7391  */
7392 static void end_reshape(struct r5conf *conf)
7393 {
7394
7395         if (!test_bit(MD_RECOVERY_INTR, &conf->mddev->recovery)) {
7396                 struct md_rdev *rdev;
7397
7398                 spin_lock_irq(&conf->device_lock);
7399                 conf->previous_raid_disks = conf->raid_disks;
7400                 rdev_for_each(rdev, conf->mddev)
7401                         rdev->data_offset = rdev->new_data_offset;
7402                 smp_wmb();
7403                 conf->reshape_progress = MaxSector;
7404                 spin_unlock_irq(&conf->device_lock);
7405                 wake_up(&conf->wait_for_overlap);
7406
7407                 /* read-ahead size must cover two whole stripes, which is
7408                  * 2 * (datadisks) * chunksize where 'n' is the number of raid devices
7409                  */
7410                 if (conf->mddev->queue) {
7411                         int data_disks = conf->raid_disks - conf->max_degraded;
7412                         int stripe = data_disks * ((conf->chunk_sectors << 9)
7413                                                    / PAGE_SIZE);
7414                         if (conf->mddev->queue->backing_dev_info.ra_pages < 2 * stripe)
7415                                 conf->mddev->queue->backing_dev_info.ra_pages = 2 * stripe;
7416                 }
7417         }
7418 }
7419
7420 /* This is called from the raid5d thread with mddev_lock held.
7421  * It makes config changes to the device.
7422  */
7423 static void raid5_finish_reshape(struct mddev *mddev)
7424 {
7425         struct r5conf *conf = mddev->private;
7426
7427         if (!test_bit(MD_RECOVERY_INTR, &mddev->recovery)) {
7428
7429                 if (mddev->delta_disks > 0) {
7430                         md_set_array_sectors(mddev, raid5_size(mddev, 0, 0));
7431                         set_capacity(mddev->gendisk, mddev->array_sectors);
7432                         revalidate_disk(mddev->gendisk);
7433                 } else {
7434                         int d;
7435                         spin_lock_irq(&conf->device_lock);
7436                         mddev->degraded = calc_degraded(conf);
7437                         spin_unlock_irq(&conf->device_lock);
7438                         for (d = conf->raid_disks ;
7439                              d < conf->raid_disks - mddev->delta_disks;
7440                              d++) {
7441                                 struct md_rdev *rdev = conf->disks[d].rdev;
7442                                 if (rdev)
7443                                         clear_bit(In_sync, &rdev->flags);
7444                                 rdev = conf->disks[d].replacement;
7445                                 if (rdev)
7446                                         clear_bit(In_sync, &rdev->flags);
7447                         }
7448                 }
7449                 mddev->layout = conf->algorithm;
7450                 mddev->chunk_sectors = conf->chunk_sectors;
7451                 mddev->reshape_position = MaxSector;
7452                 mddev->delta_disks = 0;
7453                 mddev->reshape_backwards = 0;
7454         }
7455 }
7456
7457 static void raid5_quiesce(struct mddev *mddev, int state)
7458 {
7459         struct r5conf *conf = mddev->private;
7460
7461         switch(state) {
7462         case 2: /* resume for a suspend */
7463                 wake_up(&conf->wait_for_overlap);
7464                 break;
7465
7466         case 1: /* stop all writes */
7467                 lock_all_device_hash_locks_irq(conf);
7468                 /* '2' tells resync/reshape to pause so that all
7469                  * active stripes can drain
7470                  */
7471                 conf->quiesce = 2;
7472                 wait_event_cmd(conf->wait_for_stripe,
7473                                     atomic_read(&conf->active_stripes) == 0 &&
7474                                     atomic_read(&conf->active_aligned_reads) == 0,
7475                                     unlock_all_device_hash_locks_irq(conf),
7476                                     lock_all_device_hash_locks_irq(conf));
7477                 conf->quiesce = 1;
7478                 unlock_all_device_hash_locks_irq(conf);
7479                 /* allow reshape to continue */
7480                 wake_up(&conf->wait_for_overlap);
7481                 break;
7482
7483         case 0: /* re-enable writes */
7484                 lock_all_device_hash_locks_irq(conf);
7485                 conf->quiesce = 0;
7486                 wake_up(&conf->wait_for_stripe);
7487                 wake_up(&conf->wait_for_overlap);
7488                 unlock_all_device_hash_locks_irq(conf);
7489                 break;
7490         }
7491 }
7492
7493 static void *raid45_takeover_raid0(struct mddev *mddev, int level)
7494 {
7495         struct r0conf *raid0_conf = mddev->private;
7496         sector_t sectors;
7497
7498         /* for raid0 takeover only one zone is supported */
7499         if (raid0_conf->nr_strip_zones > 1) {
7500                 printk(KERN_ERR "md/raid:%s: cannot takeover raid0 with more than one zone.\n",
7501                        mdname(mddev));
7502                 return ERR_PTR(-EINVAL);
7503         }
7504
7505         sectors = raid0_conf->strip_zone[0].zone_end;
7506         sector_div(sectors, raid0_conf->strip_zone[0].nb_dev);
7507         mddev->dev_sectors = sectors;
7508         mddev->new_level = level;
7509         mddev->new_layout = ALGORITHM_PARITY_N;
7510         mddev->new_chunk_sectors = mddev->chunk_sectors;
7511         mddev->raid_disks += 1;
7512         mddev->delta_disks = 1;
7513         /* make sure it will be not marked as dirty */
7514         mddev->recovery_cp = MaxSector;
7515
7516         return setup_conf(mddev);
7517 }
7518
7519 static void *raid5_takeover_raid1(struct mddev *mddev)
7520 {
7521         int chunksect;
7522
7523         if (mddev->raid_disks != 2 ||
7524             mddev->degraded > 1)
7525                 return ERR_PTR(-EINVAL);
7526
7527         /* Should check if there are write-behind devices? */
7528
7529         chunksect = 64*2; /* 64K by default */
7530
7531         /* The array must be an exact multiple of chunksize */
7532         while (chunksect && (mddev->array_sectors & (chunksect-1)))
7533                 chunksect >>= 1;
7534
7535         if ((chunksect<<9) < STRIPE_SIZE)
7536                 /* array size does not allow a suitable chunk size */
7537                 return ERR_PTR(-EINVAL);
7538
7539         mddev->new_level = 5;
7540         mddev->new_layout = ALGORITHM_LEFT_SYMMETRIC;
7541         mddev->new_chunk_sectors = chunksect;
7542
7543         return setup_conf(mddev);
7544 }
7545
7546 static void *raid5_takeover_raid6(struct mddev *mddev)
7547 {
7548         int new_layout;
7549
7550         switch (mddev->layout) {
7551         case ALGORITHM_LEFT_ASYMMETRIC_6:
7552                 new_layout = ALGORITHM_LEFT_ASYMMETRIC;
7553                 break;
7554         case ALGORITHM_RIGHT_ASYMMETRIC_6:
7555                 new_layout = ALGORITHM_RIGHT_ASYMMETRIC;
7556                 break;
7557         case ALGORITHM_LEFT_SYMMETRIC_6:
7558                 new_layout = ALGORITHM_LEFT_SYMMETRIC;
7559                 break;
7560         case ALGORITHM_RIGHT_SYMMETRIC_6:
7561                 new_layout = ALGORITHM_RIGHT_SYMMETRIC;
7562                 break;
7563         case ALGORITHM_PARITY_0_6:
7564                 new_layout = ALGORITHM_PARITY_0;
7565                 break;
7566         case ALGORITHM_PARITY_N:
7567                 new_layout = ALGORITHM_PARITY_N;
7568                 break;
7569         default:
7570                 return ERR_PTR(-EINVAL);
7571         }
7572         mddev->new_level = 5;
7573         mddev->new_layout = new_layout;
7574         mddev->delta_disks = -1;
7575         mddev->raid_disks -= 1;
7576         return setup_conf(mddev);
7577 }
7578
7579 static int raid5_check_reshape(struct mddev *mddev)
7580 {
7581         /* For a 2-drive array, the layout and chunk size can be changed
7582          * immediately as not restriping is needed.
7583          * For larger arrays we record the new value - after validation
7584          * to be used by a reshape pass.
7585          */
7586         struct r5conf *conf = mddev->private;
7587         int new_chunk = mddev->new_chunk_sectors;
7588
7589         if (mddev->new_layout >= 0 && !algorithm_valid_raid5(mddev->new_layout))
7590                 return -EINVAL;
7591         if (new_chunk > 0) {
7592                 if (!is_power_of_2(new_chunk))
7593                         return -EINVAL;
7594                 if (new_chunk < (PAGE_SIZE>>9))
7595                         return -EINVAL;
7596                 if (mddev->array_sectors & (new_chunk-1))
7597                         /* not factor of array size */
7598                         return -EINVAL;
7599         }
7600
7601         /* They look valid */
7602
7603         if (mddev->raid_disks == 2) {
7604                 /* can make the change immediately */
7605                 if (mddev->new_layout >= 0) {
7606                         conf->algorithm = mddev->new_layout;
7607                         mddev->layout = mddev->new_layout;
7608                 }
7609                 if (new_chunk > 0) {
7610                         conf->chunk_sectors = new_chunk ;
7611                         mddev->chunk_sectors = new_chunk;
7612                 }
7613                 set_bit(MD_CHANGE_DEVS, &mddev->flags);
7614                 md_wakeup_thread(mddev->thread);
7615         }
7616         return check_reshape(mddev);
7617 }
7618
7619 static int raid6_check_reshape(struct mddev *mddev)
7620 {
7621         int new_chunk = mddev->new_chunk_sectors;
7622
7623         if (mddev->new_layout >= 0 && !algorithm_valid_raid6(mddev->new_layout))
7624                 return -EINVAL;
7625         if (new_chunk > 0) {
7626                 if (!is_power_of_2(new_chunk))
7627                         return -EINVAL;
7628                 if (new_chunk < (PAGE_SIZE >> 9))
7629                         return -EINVAL;
7630                 if (mddev->array_sectors & (new_chunk-1))
7631                         /* not factor of array size */
7632                         return -EINVAL;
7633         }
7634
7635         /* They look valid */
7636         return check_reshape(mddev);
7637 }
7638
7639 static void *raid5_takeover(struct mddev *mddev)
7640 {
7641         /* raid5 can take over:
7642          *  raid0 - if there is only one strip zone - make it a raid4 layout
7643          *  raid1 - if there are two drives.  We need to know the chunk size
7644          *  raid4 - trivial - just use a raid4 layout.
7645          *  raid6 - Providing it is a *_6 layout
7646          */
7647         if (mddev->level == 0)
7648                 return raid45_takeover_raid0(mddev, 5);
7649         if (mddev->level == 1)
7650                 return raid5_takeover_raid1(mddev);
7651         if (mddev->level == 4) {
7652                 mddev->new_layout = ALGORITHM_PARITY_N;
7653                 mddev->new_level = 5;
7654                 return setup_conf(mddev);
7655         }
7656         if (mddev->level == 6)
7657                 return raid5_takeover_raid6(mddev);
7658
7659         return ERR_PTR(-EINVAL);
7660 }
7661
7662 static void *raid4_takeover(struct mddev *mddev)
7663 {
7664         /* raid4 can take over:
7665          *  raid0 - if there is only one strip zone
7666          *  raid5 - if layout is right
7667          */
7668         if (mddev->level == 0)
7669                 return raid45_takeover_raid0(mddev, 4);
7670         if (mddev->level == 5 &&
7671             mddev->layout == ALGORITHM_PARITY_N) {
7672                 mddev->new_layout = 0;
7673                 mddev->new_level = 4;
7674                 return setup_conf(mddev);
7675         }
7676         return ERR_PTR(-EINVAL);
7677 }
7678
7679 static struct md_personality raid5_personality;
7680
7681 static void *raid6_takeover(struct mddev *mddev)
7682 {
7683         /* Currently can only take over a raid5.  We map the
7684          * personality to an equivalent raid6 personality
7685          * with the Q block at the end.
7686          */
7687         int new_layout;
7688
7689         if (mddev->pers != &raid5_personality)
7690                 return ERR_PTR(-EINVAL);
7691         if (mddev->degraded > 1)
7692                 return ERR_PTR(-EINVAL);
7693         if (mddev->raid_disks > 253)
7694                 return ERR_PTR(-EINVAL);
7695         if (mddev->raid_disks < 3)
7696                 return ERR_PTR(-EINVAL);
7697
7698         switch (mddev->layout) {
7699         case ALGORITHM_LEFT_ASYMMETRIC:
7700                 new_layout = ALGORITHM_LEFT_ASYMMETRIC_6;
7701                 break;
7702         case ALGORITHM_RIGHT_ASYMMETRIC:
7703                 new_layout = ALGORITHM_RIGHT_ASYMMETRIC_6;
7704                 break;
7705         case ALGORITHM_LEFT_SYMMETRIC:
7706                 new_layout = ALGORITHM_LEFT_SYMMETRIC_6;
7707                 break;
7708         case ALGORITHM_RIGHT_SYMMETRIC:
7709                 new_layout = ALGORITHM_RIGHT_SYMMETRIC_6;
7710                 break;
7711         case ALGORITHM_PARITY_0:
7712                 new_layout = ALGORITHM_PARITY_0_6;
7713                 break;
7714         case ALGORITHM_PARITY_N:
7715                 new_layout = ALGORITHM_PARITY_N;
7716                 break;
7717         default:
7718                 return ERR_PTR(-EINVAL);
7719         }
7720         mddev->new_level = 6;
7721         mddev->new_layout = new_layout;
7722         mddev->delta_disks = 1;
7723         mddev->raid_disks += 1;
7724         return setup_conf(mddev);
7725 }
7726
7727 static struct md_personality raid6_personality =
7728 {
7729         .name           = "raid6",
7730         .level          = 6,
7731         .owner          = THIS_MODULE,
7732         .make_request   = make_request,
7733         .run            = run,
7734         .free           = raid5_free,
7735         .status         = status,
7736         .error_handler  = error,
7737         .hot_add_disk   = raid5_add_disk,
7738         .hot_remove_disk= raid5_remove_disk,
7739         .spare_active   = raid5_spare_active,
7740         .sync_request   = sync_request,
7741         .resize         = raid5_resize,
7742         .size           = raid5_size,
7743         .check_reshape  = raid6_check_reshape,
7744         .start_reshape  = raid5_start_reshape,
7745         .finish_reshape = raid5_finish_reshape,
7746         .quiesce        = raid5_quiesce,
7747         .takeover       = raid6_takeover,
7748         .congested      = raid5_congested,
7749         .mergeable_bvec = raid5_mergeable_bvec,
7750 };
7751 static struct md_personality raid5_personality =
7752 {
7753         .name           = "raid5",
7754         .level          = 5,
7755         .owner          = THIS_MODULE,
7756         .make_request   = make_request,
7757         .run            = run,
7758         .free           = raid5_free,
7759         .status         = status,
7760         .error_handler  = error,
7761         .hot_add_disk   = raid5_add_disk,
7762         .hot_remove_disk= raid5_remove_disk,
7763         .spare_active   = raid5_spare_active,
7764         .sync_request   = sync_request,
7765         .resize         = raid5_resize,
7766         .size           = raid5_size,
7767         .check_reshape  = raid5_check_reshape,
7768         .start_reshape  = raid5_start_reshape,
7769         .finish_reshape = raid5_finish_reshape,
7770         .quiesce        = raid5_quiesce,
7771         .takeover       = raid5_takeover,
7772         .congested      = raid5_congested,
7773         .mergeable_bvec = raid5_mergeable_bvec,
7774 };
7775
7776 static struct md_personality raid4_personality =
7777 {
7778         .name           = "raid4",
7779         .level          = 4,
7780         .owner          = THIS_MODULE,
7781         .make_request   = make_request,
7782         .run            = run,
7783         .free           = raid5_free,
7784         .status         = status,
7785         .error_handler  = error,
7786         .hot_add_disk   = raid5_add_disk,
7787         .hot_remove_disk= raid5_remove_disk,
7788         .spare_active   = raid5_spare_active,
7789         .sync_request   = sync_request,
7790         .resize         = raid5_resize,
7791         .size           = raid5_size,
7792         .check_reshape  = raid5_check_reshape,
7793         .start_reshape  = raid5_start_reshape,
7794         .finish_reshape = raid5_finish_reshape,
7795         .quiesce        = raid5_quiesce,
7796         .takeover       = raid4_takeover,
7797         .congested      = raid5_congested,
7798         .mergeable_bvec = raid5_mergeable_bvec,
7799 };
7800
7801 static int __init raid5_init(void)
7802 {
7803         raid5_wq = alloc_workqueue("raid5wq",
7804                 WQ_UNBOUND|WQ_MEM_RECLAIM|WQ_CPU_INTENSIVE|WQ_SYSFS, 0);
7805         if (!raid5_wq)
7806                 return -ENOMEM;
7807         register_md_personality(&raid6_personality);
7808         register_md_personality(&raid5_personality);
7809         register_md_personality(&raid4_personality);
7810         return 0;
7811 }
7812
7813 static void raid5_exit(void)
7814 {
7815         unregister_md_personality(&raid6_personality);
7816         unregister_md_personality(&raid5_personality);
7817         unregister_md_personality(&raid4_personality);
7818         destroy_workqueue(raid5_wq);
7819 }
7820
7821 module_init(raid5_init);
7822 module_exit(raid5_exit);
7823 MODULE_LICENSE("GPL");
7824 MODULE_DESCRIPTION("RAID4/5/6 (striping with parity) personality for MD");
7825 MODULE_ALIAS("md-personality-4"); /* RAID5 */
7826 MODULE_ALIAS("md-raid5");
7827 MODULE_ALIAS("md-raid4");
7828 MODULE_ALIAS("md-level-5");
7829 MODULE_ALIAS("md-level-4");
7830 MODULE_ALIAS("md-personality-8"); /* RAID6 */
7831 MODULE_ALIAS("md-raid6");
7832 MODULE_ALIAS("md-level-6");
7833
7834 /* This used to be two separate modules, they were: */
7835 MODULE_ALIAS("raid5");
7836 MODULE_ALIAS("raid6");